rubycdp · Mifrill · Jan 7, 2022 · Jan 7, 2022 · Jan 7, 2022 · Jan 12, 2022
diff --git 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
@@ -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/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
@@ -36,6 +36,34 @@ 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) {

diff --git 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)

diff --git 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
@@ -504,6 +504,78 @@ 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 "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")).not_to be_nil
+      end
+
+      it "waits for provided css hidden selector" do
+        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']")).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']")).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)
+        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)).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']").frame
+        expect(frame.wait_for_selector(xpath: "//div[@id='wait_for_selector_within_frame']")).not_to be_nil
+      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/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|

diff --git 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>