In this post we will discuss Selenium Webdriver JavascriptExecutor examples.

JavascriptExecutor

JavascriptExecutor is an interface indicating that the WebDriver can execute JavaScript and providing access to the mechanism to do so. This method executes JavaScript in the context of the currently selected frame or window. As a result,the script fragment provided will be executed as the body of an anonymous function.

Same origin policy : Because of cross domain policies browsers enforce your script execution may fail unexpectedly  and without adequate error messaging.

executeScript()

We can pass the script the JavaScript to execute by the method.This method executes JavaScript in the context of the currently selected frame or window.As a result,the script  provided will be executed as the body of an anonymous function. Furthermore, one can use document within the script, to refer to the current document.

Example:

JavascriptExecutor jscript = (JavascriptExecutor)driver;
jscript.executeScript("scroll(0, 500)");

We can even pass arguments . Furthermore, arguments must be a number, a boolean, a String, WebElement, or a List of any combination. Also, an exception will be thrown if the arguments do not meet these criteria. Also, the arguments will be made available to the JavaScript via the “arguments” magic variable.

Example:

if (webdriver instanceof JavascriptExecutor)
 {
  ((JavascriptExecutor)webdriver).executeScript("arguments[0].
style.border='6px solid green'", webelement);
}

 

executeAsyncScript()

Execute an asynchronous piece of JavaScript in the context of the currently selected frame or window. Unlike executing  executeScript synchronous JavaScript, scripts executed with this method must explicitly signal they are finished by invoking the provided callback. This callback is always injected into the executed function as the last argument.

The first argument passed to the callback function will be used as the script’s result.Also,the default timeout for a script to be executed is 0ms.Most of all, one must set the script timeout beforehand to a sufficiently large value.

Example:

Performing a sleep in the browser under test.

 long start = System.currentTimeMillis();
      ((JavascriptExecutor) driver).executeAsyncScript(
          "window.setTimeout(arguments[arguments.length - 1], 750);");
      System.out.println(
          "Elapsed time: " + System.currentTimeMillis() - start);
    }

AJAX request is usually sent using XMLHttpRequest and wait for the ready state for the callback.
We will discuss about AJAX in later post.
In conclusion, I hope your are now clear how to execute javascript using Selenium webdriver.