From c58767fd639e6816fd3b62409ae0b4d4d4afae6e Mon Sep 17 00:00:00 2001
From: Aleksey Strizhak <alexei.mifrill.strizhak@gmail.com>
Date: Fri, 7 Jan 2022 05:28:54 +0500
Subject: [PATCH 01/12] extend evaluate_func with any options ability

---
 lib/ferrum/frame/runtime.rb | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/lib/ferrum/frame/runtime.rb b/lib/ferrum/frame/runtime.rb
index 926cc783..cbd351fe 100644
--- a/lib/ferrum/frame/runtime.rb
+++ b/lib/ferrum/frame/runtime.rb
@@ -76,8 +76,8 @@ def execute(expression, *args)
         true
       end
 
-      def evaluate_func(expression, *args, on: nil)
-        call(expression: expression, arguments: args, on: on)
+      def evaluate_func(expression, *args, on: nil, **options)
+        call(expression: expression, arguments: args, on: on, **options)
       end
 
       def evaluate_on(node:, expression:, by_value: true, wait: 0)

From 83ca882255aca06d75ef5884d854903cd10be16d Mon Sep 17 00:00:00 2001
From: Aleksey Strizhak <alexei.mifrill.strizhak@gmail.com>
Date: Fri, 7 Jan 2022 05:36:53 +0500
Subject: [PATCH 02/12] implement #wait_for_selector method for browser

---
 lib/ferrum/browser.rb          |  2 +-
 lib/ferrum/frame/dom.rb        | 30 ++++++++++++++++++
 lib/ferrum/page.rb             |  2 +-
 spec/browser_spec.rb           | 58 ++++++++++++++++++++++++++++++++++
 spec/support/views/with_js.erb | 17 ++++++++++
 5 files changed, 107 insertions(+), 2 deletions(-)

diff --git a/lib/ferrum/browser.rb b/lib/ferrum/browser.rb
index 8926195f..751366cf 100644
--- a/lib/ferrum/browser.rb
+++ b/lib/ferrum/browser.rb
@@ -28,7 +28,7 @@ class Browser
                 evaluate evaluate_on evaluate_async execute evaluate_func
                 add_script_tag add_style_tag bypass_csp
                 on goto position position=
-                playback_rate playback_rate=] => :page
+                playback_rate playback_rate= wait_for_selector] => :page
     delegate %i[default_user_agent] => :process
 
     attr_reader :client, :process, :contexts, :logger, :js_errors, :pending_connection_errors,
diff --git a/lib/ferrum/frame/dom.rb b/lib/ferrum/frame/dom.rb
index b60c6b0a..95835fa7 100644
--- a/lib/ferrum/frame/dom.rb
+++ b/lib/ferrum/frame/dom.rb
@@ -36,6 +36,36 @@ def body
         evaluate("document.documentElement.outerHTML")
       end
 
+      def wait_for_selector(css: nil, xpath: nil, timeout: 1000, interval: 100)
+        tap do
+          evaluate_func(%(
+            function(selector, isXpath, timeout, interval) {
+              var attempts = 0;
+              var max = timeout / interval;
+              function waitForSelector(resolve, reject) {
+                if (attempts > ((max < 1) ? 1 : max)) {
+                  return reject(new Error("Not found element match the selector:" + selector));
+                }
+                var element = isXpath
+                  ? document.
+                      evaluate(selector, document, null, XPathResult.FIRST_ORDERED_NODE_TYPE, null).singleNodeValue
+                  : document.querySelector(selector);
+                if (element !== null) {
+                  return resolve(element);
+                }
+                setTimeout(function () {
+                  waitForSelector(resolve, reject);
+                }, interval);
+                attempts++;
+              }
+              return new Promise(function (resolve, reject) {
+                waitForSelector(resolve, reject);
+              });
+            }
+          ), css || xpath, css.nil? && !xpath.nil?, timeout, interval, awaitPromise: true)
+        end
+      end
+
       def xpath(selector, within: nil)
         expr = <<~JS
           function(selector, within) {
diff --git a/lib/ferrum/page.rb b/lib/ferrum/page.rb
index 5a5c25f7..52db751d 100644
--- a/lib/ferrum/page.rb
+++ b/lib/ferrum/page.rb
@@ -34,7 +34,7 @@ def reset
     delegate %i[at_css at_xpath css xpath
                 current_url current_title url title body doctype content=
                 execution_id evaluate evaluate_on evaluate_async execute evaluate_func
-                add_script_tag add_style_tag] => :main_frame
+                add_script_tag add_style_tag wait_for_selector] => :main_frame
 
     include Animation
     include Screenshot
diff --git a/spec/browser_spec.rb b/spec/browser_spec.rb
index 7bc6672e..b7193182 100644
--- a/spec/browser_spec.rb
+++ b/spec/browser_spec.rb
@@ -504,6 +504,64 @@ module Ferrum
       expect(browser.evaluate("window.last_hashchange")).to eq("#foo")
     end
 
+    context "wait_for_selector" do
+      before do
+        browser.go_to("/ferrum/with_js")
+      end
+
+      it "waits for provided css selector" do
+        expect(
+          browser.wait_for_selector(css: "div#wait_for_selector").at_css("div#wait_for_selector")
+        ).not_to be_nil
+      end
+
+      it "waits for provided css hidden selector" do
+        expect(
+          browser.wait_for_selector(css: "div#wait_for_hidden_selector").at_css("div#wait_for_hidden_selector")
+        ).not_to be_nil
+      end
+
+      it "waits for provided xpath selector" do
+        expect(
+          browser.wait_for_selector(xpath: "//div[@id='wait_for_selector']").at_css("div#wait_for_selector")
+        ).not_to be_nil
+      end
+
+      it "waits for provided xpath hidden selector" do
+        expect(
+          browser
+            .wait_for_selector(xpath: "//div[@id='wait_for_hidden_selector']")
+            .at_css("div#wait_for_hidden_selector")
+        ).not_to be_nil
+      end
+
+      it "raises error when timeout exceed" do
+        expect do
+          browser.wait_for_selector(css: "div#wait_for_selector", timeout: 800)
+        end.to raise_error(Ferrum::JavaScriptError, /Not found element match the selector/)
+      end
+
+      it "raises error when provided invalid css" do
+        expect do
+          browser.wait_for_selector(css: "//div[@id='wait_for_selector']")
+        end.to raise_error(Ferrum::JavaScriptError, /Failed to execute 'querySelector' on 'Document'/)
+      end
+
+      it "raises error when provided invalid xpath" do
+        expect do
+          browser.wait_for_selector(xpath: "div#wait_for_selector")
+        end.to raise_error(Ferrum::JavaScriptError, /Failed to execute 'evaluate' on 'Document'/)
+      end
+
+      it "waits less than provided timeout when node found" do
+        Timeout.timeout(1) do
+          expect(
+            browser.wait_for_selector(css: "div#wait_for_selector", timeout: 2000).at_css("div#wait_for_selector")
+          ).not_to be_nil
+        end
+      end
+    end
+
     context "current_url" do
       it "supports whitespace characters" do
         browser.go_to("/ferrum/arbitrary_path/200/foo%20bar%20baz")
diff --git a/spec/support/views/with_js.erb b/spec/support/views/with_js.erb
index 2ddefe35..50375efe 100644
--- a/spec/support/views/with_js.erb
+++ b/spec/support/views/with_js.erb
@@ -24,6 +24,23 @@
         display: inline;
       }
     </style>
+    <script>
+      $(document).ready(function(){
+        setTimeout(function(){
+          const div = document.createElement('div');
+          div.setAttribute('id', 'wait_for_selector');
+          document.body.appendChild(div);
+        }, 900);
+      });
+      $(document).ready(function(){
+        setTimeout(function(){
+          const div = document.createElement('div');
+          div.setAttribute('id', 'wait_for_hidden_selector');
+          div.setAttribute('style', 'display:none;');
+          document.body.appendChild(div);
+        }, 900);
+      });
+    </script>
   </head>
 
   <body>

From 051617d14bcbf8fd2081e1059e920a99cdcf3cee Mon Sep 17 00:00:00 2001
From: Aleksey Strizhak <alexei.mifrill.strizhak@gmail.com>
Date: Fri, 7 Jan 2022 05:57:21 +0500
Subject: [PATCH 03/12] fix spec with hardcoded value of size for with_js view
 due to added lines

---
 spec/network/response_spec.rb | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/spec/network/response_spec.rb b/spec/network/response_spec.rb
index 6b65739f..588e497e 100644
--- a/spec/network/response_spec.rb
+++ b/spec/network/response_spec.rb
@@ -42,7 +42,7 @@ class Network
           %r{/ferrum/jquery.min.js$} => File.size("#{PROJECT_ROOT}/spec/support/public/jquery-1.11.3.min.js"),
           %r{/ferrum/jquery-ui.min.js$} => File.size("#{PROJECT_ROOT}/spec/support/public/jquery-ui-1.11.4.min.js"),
           %r{/ferrum/test.js$} => File.size("#{PROJECT_ROOT}/spec/support/public/test.js"),
-          %r{/ferrum/with_js$} => 2343
+          %r{/ferrum/with_js$} => 2919
         }
 
         resources_size.each do |resource, size|

From 8d98b79952e443b108713c495adf4c09e00c9123 Mon Sep 17 00:00:00 2001
From: Aleksey Strizhak <alexei.mifrill.strizhak@gmail.com>
Date: Wed, 12 Jan 2022 17:26:02 +0500
Subject: [PATCH 04/12] increase default timeout to 5 sec

---
 lib/ferrum/frame/dom.rb | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/lib/ferrum/frame/dom.rb b/lib/ferrum/frame/dom.rb
index 95835fa7..f9186ade 100644
--- a/lib/ferrum/frame/dom.rb
+++ b/lib/ferrum/frame/dom.rb
@@ -36,7 +36,7 @@ def body
         evaluate("document.documentElement.outerHTML")
       end
 
-      def wait_for_selector(css: nil, xpath: nil, timeout: 1000, interval: 100)
+      def wait_for_selector(css: nil, xpath: nil, timeout: 5000, interval: 100)
         tap do
           evaluate_func(%(
             function(selector, isXpath, timeout, interval) {
@@ -44,7 +44,7 @@ def wait_for_selector(css: nil, xpath: nil, timeout: 1000, interval: 100)
               var max = timeout / interval;
               function waitForSelector(resolve, reject) {
                 if (attempts > ((max < 1) ? 1 : max)) {
-                  return reject(new Error("Not found element match the selector:" + selector));
+                  return reject(new Error("Not found element match the selector: " + selector));
                 }
                 var element = isXpath
                   ? document.

From 0f0fbe0a2dcf8bef9ad2f541d6b21a3f168e5ea3 Mon Sep 17 00:00:00 2001
From: Aleksey Strizhak <alexei.mifrill.strizhak@gmail.com>
Date: Sat, 15 Jan 2022 11:05:41 +0500
Subject: [PATCH 05/12] add spec: 'waits for selector within frame'

---
 spec/browser_spec.rb | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/spec/browser_spec.rb b/spec/browser_spec.rb
index b7193182..409601eb 100644
--- a/spec/browser_spec.rb
+++ b/spec/browser_spec.rb
@@ -560,6 +560,25 @@ module Ferrum
           ).not_to be_nil
         end
       end
+
+      it "waits for selector within frame" do
+        browser.execute <<-JS
+          setTimeout(function(){
+            document.body.innerHTML += "<iframe src='about:blank' name='frame'>";
+            var iframeDocument = document.querySelector("iframe[name='frame']").contentWindow.document;
+            var content = "<html><body><div id='wait_for_selector_within_frame'></div></body></html>";
+            iframeDocument.open("text/html", "replace");
+            iframeDocument.write(content);
+            iframeDocument.close();
+          }, 900);
+        JS
+        frame = browser.wait_for_selector(xpath: "//iframe[@name='frame']").at_xpath("//iframe[@name='frame']").frame
+        expect(
+          frame
+            .wait_for_selector(xpath: "//div[@id='wait_for_selector_within_frame']")
+            .at_css("div#wait_for_selector_within_frame")
+        ).not_to be_nil
+      end
     end
 
     context "current_url" do

From 53edf60a37c7d00a9284c59859963492071132f5 Mon Sep 17 00:00:00 2001
From: Aleksey Strizhak <alexei.mifrill.strizhak@gmail.com>
Date: Sat, 15 Jan 2022 11:21:22 +0500
Subject: [PATCH 06/12] returns Node instead DOM instance in wait_for_selector
 method

---
 lib/ferrum/frame/dom.rb | 46 ++++++++++++++++++++---------------------
 spec/browser_spec.rb    | 35 +++++++++++--------------------
 2 files changed, 34 insertions(+), 47 deletions(-)

diff --git a/lib/ferrum/frame/dom.rb b/lib/ferrum/frame/dom.rb
index f9186ade..37886d8f 100644
--- a/lib/ferrum/frame/dom.rb
+++ b/lib/ferrum/frame/dom.rb
@@ -37,33 +37,31 @@ def body
       end
 
       def wait_for_selector(css: nil, xpath: nil, timeout: 5000, interval: 100)
-        tap do
-          evaluate_func(%(
-            function(selector, isXpath, timeout, interval) {
-              var attempts = 0;
-              var max = timeout / interval;
-              function waitForSelector(resolve, reject) {
-                if (attempts > ((max < 1) ? 1 : max)) {
-                  return reject(new Error("Not found element match the selector: " + selector));
-                }
-                var element = isXpath
-                  ? document.
-                      evaluate(selector, document, null, XPathResult.FIRST_ORDERED_NODE_TYPE, null).singleNodeValue
-                  : document.querySelector(selector);
-                if (element !== null) {
-                  return resolve(element);
-                }
-                setTimeout(function () {
-                  waitForSelector(resolve, reject);
-                }, interval);
-                attempts++;
+        evaluate_func(%(
+          function(selector, isXpath, timeout, interval) {
+            var attempts = 0;
+            var max = timeout / interval;
+            function waitForSelector(resolve, reject) {
+              if (attempts > ((max < 1) ? 1 : max)) {
+                return reject(new Error("Not found element match the selector: " + selector));
               }
-              return new Promise(function (resolve, reject) {
+              var element = isXpath
+                ? document.
+                  evaluate(selector, document, null, XPathResult.FIRST_ORDERED_NODE_TYPE, null).singleNodeValue
+                : document.querySelector(selector);
+              if (element !== null) {
+                return resolve(element);
+              }
+              setTimeout(function () {
                 waitForSelector(resolve, reject);
-              });
+              }, interval);
+              attempts++;
             }
-          ), css || xpath, css.nil? && !xpath.nil?, timeout, interval, awaitPromise: true)
-        end
+            return new Promise(function (resolve, reject) {
+              waitForSelector(resolve, reject);
+            });
+          }
+        ), css || xpath, css.nil? && !xpath.nil?, timeout, interval, awaitPromise: true)
       end
 
       def xpath(selector, within: nil)
diff --git a/spec/browser_spec.rb b/spec/browser_spec.rb
index 409601eb..813fa2fb 100644
--- a/spec/browser_spec.rb
+++ b/spec/browser_spec.rb
@@ -509,30 +509,25 @@ module Ferrum
         browser.go_to("/ferrum/with_js")
       end
 
+      it "returns Node by provided selector" do
+        expect(browser.wait_for_selector(css: "div#wait_for_selector")).to be_kind_of(Ferrum::Node)
+        expect(browser.wait_for_selector(xpath: "//div[@id='wait_for_selector']")).to be_kind_of(Ferrum::Node)
+      end
+
       it "waits for provided css selector" do
-        expect(
-          browser.wait_for_selector(css: "div#wait_for_selector").at_css("div#wait_for_selector")
-        ).not_to be_nil
+        expect(browser.wait_for_selector(css: "div#wait_for_selector")).not_to be_nil
       end
 
       it "waits for provided css hidden selector" do
-        expect(
-          browser.wait_for_selector(css: "div#wait_for_hidden_selector").at_css("div#wait_for_hidden_selector")
-        ).not_to be_nil
+        expect(browser.wait_for_selector(css: "div#wait_for_hidden_selector")).not_to be_nil
       end
 
       it "waits for provided xpath selector" do
-        expect(
-          browser.wait_for_selector(xpath: "//div[@id='wait_for_selector']").at_css("div#wait_for_selector")
-        ).not_to be_nil
+        expect(browser.wait_for_selector(xpath: "//div[@id='wait_for_selector']")).not_to be_nil
       end
 
       it "waits for provided xpath hidden selector" do
-        expect(
-          browser
-            .wait_for_selector(xpath: "//div[@id='wait_for_hidden_selector']")
-            .at_css("div#wait_for_hidden_selector")
-        ).not_to be_nil
+        expect(browser.wait_for_selector(xpath: "//div[@id='wait_for_hidden_selector']")).not_to be_nil
       end
 
       it "raises error when timeout exceed" do
@@ -555,9 +550,7 @@ module Ferrum
 
       it "waits less than provided timeout when node found" do
         Timeout.timeout(1) do
-          expect(
-            browser.wait_for_selector(css: "div#wait_for_selector", timeout: 2000).at_css("div#wait_for_selector")
-          ).not_to be_nil
+          expect(browser.wait_for_selector(css: "div#wait_for_selector", timeout: 2000)).not_to be_nil
         end
       end
 
@@ -572,12 +565,8 @@ module Ferrum
             iframeDocument.close();
           }, 900);
         JS
-        frame = browser.wait_for_selector(xpath: "//iframe[@name='frame']").at_xpath("//iframe[@name='frame']").frame
-        expect(
-          frame
-            .wait_for_selector(xpath: "//div[@id='wait_for_selector_within_frame']")
-            .at_css("div#wait_for_selector_within_frame")
-        ).not_to be_nil
+        frame = browser.wait_for_selector(xpath: "//iframe[@name='frame']").frame
+        expect(frame.wait_for_selector(xpath: "//div[@id='wait_for_selector_within_frame']")).not_to be_nil
       end
     end
 

From cf74591384ffb8351befab380b1e07f00cf3f563 Mon Sep 17 00:00:00 2001
From: Aleksey Strizhak <alexei.mifrill.strizhak@gmail.com>
Date: Sat, 15 Jan 2022 11:22:01 +0500
Subject: [PATCH 07/12] set default timeout 3 sec

---
 lib/ferrum/frame/dom.rb | 2 +-
 spec/browser_spec.rb    | 6 ++++++
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/lib/ferrum/frame/dom.rb b/lib/ferrum/frame/dom.rb
index 37886d8f..da333a51 100644
--- a/lib/ferrum/frame/dom.rb
+++ b/lib/ferrum/frame/dom.rb
@@ -36,7 +36,7 @@ def body
         evaluate("document.documentElement.outerHTML")
       end
 
-      def wait_for_selector(css: nil, xpath: nil, timeout: 5000, interval: 100)
+      def wait_for_selector(css: nil, xpath: nil, timeout: 3000, interval: 100)
         evaluate_func(%(
           function(selector, isXpath, timeout, interval) {
             var attempts = 0;
diff --git a/spec/browser_spec.rb b/spec/browser_spec.rb
index 813fa2fb..363781a3 100644
--- a/spec/browser_spec.rb
+++ b/spec/browser_spec.rb
@@ -530,6 +530,12 @@ module Ferrum
         expect(browser.wait_for_selector(xpath: "//div[@id='wait_for_hidden_selector']")).not_to be_nil
       end
 
+      it "raises error when default timeout exceed" do
+        expect do
+          browser.wait_for_selector(css: "div#not_existed_element")
+        end.to raise_error(Ferrum::JavaScriptError, /Not found element match the selector/)
+      end
+
       it "raises error when timeout exceed" do
         expect do
           browser.wait_for_selector(css: "div#wait_for_selector", timeout: 800)

From 3b0973994d1b628f03fe9cce857ea15d6363c0c8 Mon Sep 17 00:00:00 2001
From: Aleksey Strizhak <alexei.mifrill.strizhak@gmail.com>
Date: Sat, 15 Jan 2022 15:17:44 +0500
Subject: [PATCH 08/12] fill CHANGELOG/README for implemented
 Ferrum::Browser#wait_for_selector method

---
 CHANGELOG.md            |  1 +
 README.md               | 12 ++++++++++++
 lib/ferrum/frame/dom.rb |  3 +--
 3 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 2aeaaa9d..a4659d85 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,7 @@
 
 ### Added
 
+- `Ferrum::Browser#wait_for_selector`: returns instance of `Ferrum::Node` that's matched by provided selector.
 - Alias `Ferrum::Frame#content=` to `Ferrum::Frame#set_content`
 - Alias `Ferrum::Node#propery` to `Ferrum::Node#[]`
 - Implement `Ferrum::Network#blacklist=` and `Ferrum::Network#whitelist=`
diff --git a/README.md b/README.md
index 1f70ba03..713c24a4 100644
--- a/README.md
+++ b/README.md
@@ -343,6 +343,18 @@ browser.go_to("https://google.com/")
 browser.body # => '<html itemscope="" itemtype="http://schema.org/WebPage" lang="ru"><head>...
 ```
 
+#### wait_for_selector : `Node`
+
+```ruby
+browser.wait_for_selector(css: "body", timeout: 5000) # => [Node]
+browser.wait_for_selector(xpath: "//body", interval: 200) # => [Node]
+```
+
+* options `Hash`
+  * `:css` (String) - selector in css format, not specified by default.
+  * `:xpath` (String) - selector in xpath format, not specified by default.
+  * `:timeout` (Integer) - timeout for the selector-waiting in milliseconds, 3000 ms by default.
+  * `:interval` (Integer) - interval that used to compute attempts for the selector-waiting (max attempts = timeout / interval), 100 by default.
 
 ## Screenshots
 
diff --git a/lib/ferrum/frame/dom.rb b/lib/ferrum/frame/dom.rb
index da333a51..bfea578c 100644
--- a/lib/ferrum/frame/dom.rb
+++ b/lib/ferrum/frame/dom.rb
@@ -46,8 +46,7 @@ def wait_for_selector(css: nil, xpath: nil, timeout: 3000, interval: 100)
                 return reject(new Error("Not found element match the selector: " + selector));
               }
               var element = isXpath
-                ? document.
-                  evaluate(selector, document, null, XPathResult.FIRST_ORDERED_NODE_TYPE, null).singleNodeValue
+                ? document.evaluate(selector, document, null, XPathResult.FIRST_ORDERED_NODE_TYPE, null).singleNodeValue
                 : document.querySelector(selector);
               if (element !== null) {
                 return resolve(element);

From c1537141c5336cb2fbcd331531b0f01511568326 Mon Sep 17 00:00:00 2001
From: Aleksey Strizhak <alexei.mifrill.strizhak@gmail.com>
Date: Tue, 1 Feb 2022 23:30:56 +0500
Subject: [PATCH 09/12] apply heredoc for JS expression in
 Frame::DOM#wait_for_selector for consistency

---
 lib/ferrum/frame/dom.rb | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/lib/ferrum/frame/dom.rb b/lib/ferrum/frame/dom.rb
index bfea578c..2fcc2d47 100644
--- a/lib/ferrum/frame/dom.rb
+++ b/lib/ferrum/frame/dom.rb
@@ -37,7 +37,7 @@ def body
       end
 
       def wait_for_selector(css: nil, xpath: nil, timeout: 3000, interval: 100)
-        evaluate_func(%(
+        expr = <<~JS
           function(selector, isXpath, timeout, interval) {
             var attempts = 0;
             var max = timeout / interval;
@@ -60,7 +60,8 @@ def wait_for_selector(css: nil, xpath: nil, timeout: 3000, interval: 100)
               waitForSelector(resolve, reject);
             });
           }
-        ), css || xpath, css.nil? && !xpath.nil?, timeout, interval, awaitPromise: true)
+        JS
+        evaluate_func(expr, css || xpath, css.nil? && !xpath.nil?, timeout, interval, awaitPromise: true)
       end
 
       def xpath(selector, within: nil)

From 0489d60800504d09c1ffaab9b224b0719c4a320f Mon Sep 17 00:00:00 2001
From: Aleksey Strizhak <alexei.mifrill.strizhak@gmail.com>
Date: Wed, 2 Feb 2022 01:59:48 +0500
Subject: [PATCH 10/12] refactor wait_for_selector method with
 wait_for_css/wait_for_xpath

---
 CHANGELOG.md            |  3 +-
 README.md               | 18 ++++++---
 lib/ferrum/browser.rb   |  2 +-
 lib/ferrum/frame/dom.rb | 80 +++++++++++++++++++++++++--------------
 lib/ferrum/page.rb      |  2 +-
 spec/browser_spec.rb    | 84 +++++++++++++++++++++++++++++------------
 6 files changed, 128 insertions(+), 61 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index a4659d85..64431f88 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,7 +2,8 @@
 
 ### Added
 
-- `Ferrum::Browser#wait_for_selector`: returns instance of `Ferrum::Node` that's matched by provided selector.
+- `Ferrum::Browser#wait_for_css`: returns instance of `Ferrum::Node` that's matched by provided css selector.
+- `Ferrum::Browser#wait_for_xpath`: returns instance of `Ferrum::Node` that's matched by provided XPath selector.
 - Alias `Ferrum::Frame#content=` to `Ferrum::Frame#set_content`
 - Alias `Ferrum::Node#propery` to `Ferrum::Node#[]`
 - Implement `Ferrum::Network#blacklist=` and `Ferrum::Network#whitelist=`
diff --git a/README.md b/README.md
index 713c24a4..dccb1c7b 100644
--- a/README.md
+++ b/README.md
@@ -343,16 +343,24 @@ browser.go_to("https://google.com/")
 browser.body # => '<html itemscope="" itemtype="http://schema.org/WebPage" lang="ru"><head>...
 ```
 
-#### wait_for_selector : `Node`
+#### wait_for_css : `Node`
 
 ```ruby
-browser.wait_for_selector(css: "body", timeout: 5000) # => [Node]
-browser.wait_for_selector(xpath: "//body", interval: 200) # => [Node]
+browser.wait_for_css("body", timeout: 3000, interval: 100) # => [Node]
+```
+* css `String` - CSS selector for a target element.
+* options `Hash`
+  * `:timeout` (Integer) - timeout for the selector-waiting in milliseconds, 3000 ms by default.
+  * `:interval` (Integer) - interval that used to compute attempts for the selector-waiting (max attempts = timeout / interval), 100 by default.
+
+#### wait_for_xpath : `Node`
+
+```ruby
+browser.wait_for_xpath("//body", timeout: 3000, interval: 100) # => [Node]
 ```
 
+* xpath `String` - XPath selector for a target element.
 * options `Hash`
-  * `:css` (String) - selector in css format, not specified by default.
-  * `:xpath` (String) - selector in xpath format, not specified by default.
   * `:timeout` (Integer) - timeout for the selector-waiting in milliseconds, 3000 ms by default.
   * `:interval` (Integer) - interval that used to compute attempts for the selector-waiting (max attempts = timeout / interval), 100 by default.
 
diff --git a/lib/ferrum/browser.rb b/lib/ferrum/browser.rb
index 751366cf..6456c49d 100644
--- a/lib/ferrum/browser.rb
+++ b/lib/ferrum/browser.rb
@@ -28,7 +28,7 @@ class Browser
                 evaluate evaluate_on evaluate_async execute evaluate_func
                 add_script_tag add_style_tag bypass_csp
                 on goto position position=
-                playback_rate playback_rate= wait_for_selector] => :page
+                playback_rate playback_rate= wait_for_css wait_for_xpath] => :page
     delegate %i[default_user_agent] => :process
 
     attr_reader :client, :process, :contexts, :logger, :js_errors, :pending_connection_errors,
diff --git a/lib/ferrum/frame/dom.rb b/lib/ferrum/frame/dom.rb
index 2fcc2d47..ab673bbd 100644
--- a/lib/ferrum/frame/dom.rb
+++ b/lib/ferrum/frame/dom.rb
@@ -36,34 +36,6 @@ def body
         evaluate("document.documentElement.outerHTML")
       end
 
-      def wait_for_selector(css: nil, xpath: nil, timeout: 3000, interval: 100)
-        expr = <<~JS
-          function(selector, isXpath, timeout, interval) {
-            var attempts = 0;
-            var max = timeout / interval;
-            function waitForSelector(resolve, reject) {
-              if (attempts > ((max < 1) ? 1 : max)) {
-                return reject(new Error("Not found element match the selector: " + selector));
-              }
-              var element = isXpath
-                ? document.evaluate(selector, document, null, XPathResult.FIRST_ORDERED_NODE_TYPE, null).singleNodeValue
-                : document.querySelector(selector);
-              if (element !== null) {
-                return resolve(element);
-              }
-              setTimeout(function () {
-                waitForSelector(resolve, reject);
-              }, interval);
-              attempts++;
-            }
-            return new Promise(function (resolve, reject) {
-              waitForSelector(resolve, reject);
-            });
-          }
-        JS
-        evaluate_func(expr, css || xpath, css.nil? && !xpath.nil?, timeout, interval, awaitPromise: true)
-      end
-
       def xpath(selector, within: nil)
         expr = <<~JS
           function(selector, within) {
@@ -93,6 +65,16 @@ def at_xpath(selector, within: nil)
         evaluate_func(expr, selector, within)
       end
 
+      def wait_for_xpath(xpath, **options)
+        expr = <<~JS
+          function(selector) {
+            return document.evaluate(selector, document, null, XPathResult.FIRST_ORDERED_NODE_TYPE, null).singleNodeValue;
+          }
+        JS
+
+        wait_for_selector(expr, xpath: xpath, **options)
+      end
+
       def css(selector, within: nil)
         expr = <<~JS
           function(selector, within) {
@@ -114,6 +96,48 @@ def at_css(selector, within: nil)
 
         evaluate_func(expr, selector, within)
       end
+
+      def wait_for_css(css, **options)
+        expr = <<~JS
+          function(selector) {
+            return document.querySelector(selector);
+          }
+        JS
+
+        wait_for_selector(expr, css: css, **options)
+      end
+
+      private
+
+      def wait_for_selector(find_by_selector_function, css: nil, xpath: nil, timeout: 3000, interval: 100)
+        expr = <<~JS
+          function(selector, findBySelectorFunction, timeout, interval) {
+            var attempts = 0;
+            var max = timeout / interval;
+            var wrapperFunction = function(expression) {
+              return "{ return " + expression + " };";
+            }
+            function waitForElement(resolve, reject) {
+              if (attempts > ((max < 1) ? 1 : max)) {
+                return reject(new Error("Not found element match the selector: " + selector));
+              }
+              var element = new Function(wrapperFunction(findBySelectorFunction))()(selector);
+              if (element !== null) {
+                return resolve(element);
+              }
+              setTimeout(function () {
+                waitForElement(resolve, reject);
+              }, interval);
+              attempts++;
+            }
+            return new Promise(function (resolve, reject) {
+              waitForElement(resolve, reject);
+            });
+          }
+        JS
+
+        evaluate_func(expr, css || xpath, find_by_selector_function, timeout, interval, awaitPromise: true)
+      end
     end
   end
 end
diff --git a/lib/ferrum/page.rb b/lib/ferrum/page.rb
index 52db751d..cb22d3a1 100644
--- a/lib/ferrum/page.rb
+++ b/lib/ferrum/page.rb
@@ -34,7 +34,7 @@ def reset
     delegate %i[at_css at_xpath css xpath
                 current_url current_title url title body doctype content=
                 execution_id evaluate evaluate_on evaluate_async execute evaluate_func
-                add_script_tag add_style_tag wait_for_selector] => :main_frame
+                add_script_tag add_style_tag wait_for_css wait_for_xpath] => :main_frame
 
     include Animation
     include Screenshot
diff --git a/spec/browser_spec.rb b/spec/browser_spec.rb
index 363781a3..9249bb1a 100644
--- a/spec/browser_spec.rb
+++ b/spec/browser_spec.rb
@@ -504,63 +504,97 @@ module Ferrum
       expect(browser.evaluate("window.last_hashchange")).to eq("#foo")
     end
 
-    context "wait_for_selector" do
+    context "wait_for_css" do
       before do
         browser.go_to("/ferrum/with_js")
       end
 
-      it "returns Node by provided selector" do
-        expect(browser.wait_for_selector(css: "div#wait_for_selector")).to be_kind_of(Ferrum::Node)
-        expect(browser.wait_for_selector(xpath: "//div[@id='wait_for_selector']")).to be_kind_of(Ferrum::Node)
+      it "waits for provided css selector" do
+        expect(browser.wait_for_css("div#wait_for_selector")).to be_kind_of(Ferrum::Node)
       end
 
-      it "waits for provided css selector" do
-        expect(browser.wait_for_selector(css: "div#wait_for_selector")).not_to be_nil
+      it "waits for provided css of hidden element" do
+        expect(browser.wait_for_css("div#wait_for_hidden_selector")).to be_kind_of(Ferrum::Node)
+      end
+
+      it "raises error when default timeout exceed" do
+        expect do
+          browser.wait_for_css("div#not_existed_element")
+        end.to raise_error(Ferrum::JavaScriptError, /Not found element match the selector/)
+      end
+
+      it "raises error when timeout exceed" do
+        expect do
+          browser.wait_for_css("div#wait_for_selector", timeout: 800)
+        end.to raise_error(Ferrum::JavaScriptError, /Not found element match the selector/)
+      end
+
+      it "raises error when provided invalid css selector" do
+        expect do
+          browser.wait_for_css("//div[@id='wait_for_selector']")
+        end.to raise_error(Ferrum::JavaScriptError, /Failed to execute 'querySelector' on 'Document'/)
+      end
+
+      it "waits less than provided timeout when node found" do
+        Timeout.timeout(1) do
+          expect(browser.wait_for_css("div#wait_for_selector", timeout: 2000)).to be_kind_of(Ferrum::Node)
+        end
       end
 
-      it "waits for provided css hidden selector" do
-        expect(browser.wait_for_selector(css: "div#wait_for_hidden_selector")).not_to be_nil
+      it "waits for selector within frame" do
+        browser.execute <<-JS
+          setTimeout(function(){
+            document.body.innerHTML += "<iframe src='about:blank' name='frame'>";
+            var iframeDocument = document.querySelector("iframe[name='frame']").contentWindow.document;
+            var content = "<html><body><div id='wait_for_selector_within_frame'></div></body></html>";
+            iframeDocument.open("text/html", "replace");
+            iframeDocument.write(content);
+            iframeDocument.close();
+          }, 900);
+        JS
+        frame = browser.wait_for_css("iframe[name='frame']").frame
+        expect(frame.wait_for_css("div#wait_for_selector_within_frame")).to be_kind_of(Ferrum::Node)
+      end
+    end
+
+    context "wait_for_xpath" do
+      before do
+        browser.go_to("/ferrum/with_js")
       end
 
       it "waits for provided xpath selector" do
-        expect(browser.wait_for_selector(xpath: "//div[@id='wait_for_selector']")).not_to be_nil
+        expect(browser.wait_for_xpath("//div[@id='wait_for_selector']")).to be_kind_of(Ferrum::Node)
       end
 
-      it "waits for provided xpath hidden selector" do
-        expect(browser.wait_for_selector(xpath: "//div[@id='wait_for_hidden_selector']")).not_to be_nil
+      it "waits for provided xpath of hidden element" do
+        expect(browser.wait_for_xpath("//div[@id='wait_for_hidden_selector']")).to be_kind_of(Ferrum::Node)
       end
 
       it "raises error when default timeout exceed" do
         expect do
-          browser.wait_for_selector(css: "div#not_existed_element")
+          browser.wait_for_xpath("//div[@id='not_existed_element']")
         end.to raise_error(Ferrum::JavaScriptError, /Not found element match the selector/)
       end
 
       it "raises error when timeout exceed" do
         expect do
-          browser.wait_for_selector(css: "div#wait_for_selector", timeout: 800)
+          browser.wait_for_xpath("//div[@id='wait_for_selector']", timeout: 800)
         end.to raise_error(Ferrum::JavaScriptError, /Not found element match the selector/)
       end
 
-      it "raises error when provided invalid css" do
+      it "raises error when provided invalid xpath selector" do
         expect do
-          browser.wait_for_selector(css: "//div[@id='wait_for_selector']")
-        end.to raise_error(Ferrum::JavaScriptError, /Failed to execute 'querySelector' on 'Document'/)
-      end
-
-      it "raises error when provided invalid xpath" do
-        expect do
-          browser.wait_for_selector(xpath: "div#wait_for_selector")
+          browser.wait_for_xpath("div#wait_for_selector")
         end.to raise_error(Ferrum::JavaScriptError, /Failed to execute 'evaluate' on 'Document'/)
       end
 
       it "waits less than provided timeout when node found" do
         Timeout.timeout(1) do
-          expect(browser.wait_for_selector(css: "div#wait_for_selector", timeout: 2000)).not_to be_nil
+          expect(browser.wait_for_xpath("//div[@id='wait_for_selector']", timeout: 2000)).to be_kind_of(Ferrum::Node)
         end
       end
 
-      it "waits for selector within frame" do
+      it "waits for xpath within frame" do
         browser.execute <<-JS
           setTimeout(function(){
             document.body.innerHTML += "<iframe src='about:blank' name='frame'>";
@@ -571,8 +605,8 @@ module Ferrum
             iframeDocument.close();
           }, 900);
         JS
-        frame = browser.wait_for_selector(xpath: "//iframe[@name='frame']").frame
-        expect(frame.wait_for_selector(xpath: "//div[@id='wait_for_selector_within_frame']")).not_to be_nil
+        frame = browser.wait_for_xpath("//iframe[@name='frame']").frame
+        expect(frame.wait_for_xpath("//div[@id='wait_for_selector_within_frame']")).to be_kind_of(Ferrum::Node)
       end
     end
 

From c052bd264f7886e564460064af53a0dc1a26669d Mon Sep 17 00:00:00 2001
From: Aleksey Strizhak <alexei.mifrill.strizhak@gmail.com>
Date: Wed, 2 Feb 2022 02:12:59 +0500
Subject: [PATCH 11/12] cleanup: simplify arguments calls for wait_for_selector
 method

---
 lib/ferrum/frame/dom.rb | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/lib/ferrum/frame/dom.rb b/lib/ferrum/frame/dom.rb
index ab673bbd..4d7a6565 100644
--- a/lib/ferrum/frame/dom.rb
+++ b/lib/ferrum/frame/dom.rb
@@ -72,7 +72,7 @@ def wait_for_xpath(xpath, **options)
           }
         JS
 
-        wait_for_selector(expr, xpath: xpath, **options)
+        wait_for_selector(xpath, expr, **options)
       end
 
       def css(selector, within: nil)
@@ -104,14 +104,14 @@ def wait_for_css(css, **options)
           }
         JS
 
-        wait_for_selector(expr, css: css, **options)
+        wait_for_selector(css, expr, **options)
       end
 
       private
 
-      def wait_for_selector(find_by_selector_function, css: nil, xpath: nil, timeout: 3000, interval: 100)
+      def wait_for_selector(selector, find_element_expression, timeout: 3000, interval: 100)
         expr = <<~JS
-          function(selector, findBySelectorFunction, timeout, interval) {
+          function(selector, findElementExpression, timeout, interval) {
             var attempts = 0;
             var max = timeout / interval;
             var wrapperFunction = function(expression) {
@@ -121,7 +121,7 @@ def wait_for_selector(find_by_selector_function, css: nil, xpath: nil, timeout:
               if (attempts > ((max < 1) ? 1 : max)) {
                 return reject(new Error("Not found element match the selector: " + selector));
               }
-              var element = new Function(wrapperFunction(findBySelectorFunction))()(selector);
+              var element = new Function(wrapperFunction(findElementExpression))()(selector);
               if (element !== null) {
                 return resolve(element);
               }
@@ -136,7 +136,7 @@ def wait_for_selector(find_by_selector_function, css: nil, xpath: nil, timeout:
           }
         JS
 
-        evaluate_func(expr, css || xpath, find_by_selector_function, timeout, interval, awaitPromise: true)
+        evaluate_func(expr, selector, find_element_expression, timeout, interval, awaitPromise: true)
       end
     end
   end

From 6bd16efa47584d79b303785fd585f477369157a8 Mon Sep 17 00:00:00 2001
From: Aleksey Strizhak <alexei.mifrill.strizhak@gmail.com>
Date: Wed, 2 Feb 2022 02:24:33 +0500
Subject: [PATCH 12/12] cleanup: squash wrapperFunction with findElement
 function in wait_for_selector

---
 lib/ferrum/frame/dom.rb | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/lib/ferrum/frame/dom.rb b/lib/ferrum/frame/dom.rb
index 4d7a6565..10647182 100644
--- a/lib/ferrum/frame/dom.rb
+++ b/lib/ferrum/frame/dom.rb
@@ -114,14 +114,14 @@ def wait_for_selector(selector, find_element_expression, timeout: 3000, interval
           function(selector, findElementExpression, timeout, interval) {
             var attempts = 0;
             var max = timeout / interval;
-            var wrapperFunction = function(expression) {
+            var findElement = new Function(function(expression) {
               return "{ return " + expression + " };";
-            }
+            }(findElementExpression))();
             function waitForElement(resolve, reject) {
               if (attempts > ((max < 1) ? 1 : max)) {
                 return reject(new Error("Not found element match the selector: " + selector));
               }
-              var element = new Function(wrapperFunction(findElementExpression))()(selector);
+              var element = findElement(selector);
               if (element !== null) {
                 return resolve(element);
               }