Selenium WebDriver: Wait for complex page with JavaScript to load

Question

I have a web application to test with Selenium. There is a lot of JavaScript running on page load.
This JavaScript code is not so well written but I can't change anything. So waiting for an element to appear in the DOM with findElement() method is not an option.
I want to create a generic function in Java to wait for a page to load, a possible solution would be:

• run a JavaScript script form WebDriver and store the result of document.body.innerHTML in a string variable body.
• compare the body variable to the previous version of body. if they are the same then set increment a counter notChangedCount otherwise set notChangedCount to zero.
• wait for a litte time (50 ms for example).
• if the page has not changed for some time (500 ms for example) so notChangedCount >=  10 then exit the loop otherwise loop to the first step.

Do you think it's a valid solution?

Answer 1

 In Selenium Webdriver, two conditions can be used to check if the page is loaded before finding any element on the page:

WebDriverWait wait = new WebDriverWait(driver, 50);

Using below readyState will wait till page load

wait.until((ExpectedCondition<Boolean>) wd -> ((JavascriptExecutor) wd).executeScript("return document.readyState").equals("complete")); 

Below JQuery will wait till data has not been loaded

int count =0; if((Boolean) executor.executeScript("return window.jQuery != undefined")){ while(!(Boolean) executor.executeScript("return jQuery.active == 0")){ Thread.sleep(4000); if(count>4) break; count++; } } 

After these JavaScriptCode try to findOut webElement.

WebElement we = wait.until(ExpectedConditions.presenceOfElementLocated(by)); 

Hope this helps! 

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Comments

I use JQuery, this solution worked for me!

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It worked for me.
Thanks!

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Good solution.

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findElement waits for an element to be available, but sometimes the element is available before the javascript code is initialized completely, that's why it's not an option

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Thank you for this detailed solution.

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Thanks for adding the comment. That made me understand the answer

Answer 2

You just need to wait for Javascript and jQuery to finish loading. Execute Javascript to check if jQuery.active is 0 and document.readyState is complete, which means the JS and jQuery load is complete.

public boolean waitForJStoLoad() {

    WebDriverWait wait = new WebDriverWait(driver, 30);

    // wait for jQuery to load

    ExpectedCondition<Boolean> jQueryLoad = new ExpectedCondition<Boolean>() {

      @Override

      public Boolean apply(WebDriver driver) {

        try {

          return ((Long)executeJavaScript("return jQuery.active") == 0);

        }

        catch (Exception e) {

          return true;

        }

      }

    };

    // wait for Javascript to load

    ExpectedCondition<Boolean> jsLoad = new ExpectedCondition<Boolean>() {

      @Override

      public Boolean apply(WebDriver driver) {

        return executeJavaScript("return document.readyState")

            .toString().equals("complete");

      }

    };

  return wait.until(jQueryLoad) && wait.until(jsLoad);

}

Answer 3

Hi basically you need wait for a jquery plugin execution in some element. try using the following

wait.until( new Predicate<WebDriver>() {

            public boolean apply(WebDriver driver) {
                return ((JavascriptExecutor)driver).executeScript("return document.readyState").equals("complete");
            }
        }
    );

Answer 4

You just need to check whether the JS library defines/initialize any known variable on the window or not.

If it does then you just need to wait for the variable to appear. Try using the code given below:

((JavascriptExecutor)driver).executeScript(String script, Object... args)

To test the condition like :

window.SomeClass && window.SomeClass.variable != null

and return a boolean true/false. Try wrapping this in a WebDriverWait, and wait until the script returns true.