Outline

Sometimes we cannot handle some conditions or problems with Webdriver, web controls don’t react well against selenium commands. In this kind of situations, we use Javascript. It is useful for custom synchronizations, hide or show the web elements, change values, test flash/HTML5 and so on. In order to do these, we can use Selenium’s JavascriptExecutor interface which executes JavaScript through Selenium driver. It has “executeScript” & “executeAsyncScript” methods, to run JavaScript on current browser.

Please, also check my “Selenium Webdriver wait for JavaScript JQuery and Angular” article to learn how to wait Asynchronous calls in your test automation codes.

Before sync and async JavaScript theory and examples, I want to show how to see and run javascript commands on a browser’s console tab. For example, when you go http://www.anaesthetist.com/mnm/javascript/calc.htm website you will see a calculator which is written with Javascript.

First of all, we have to enable Script and Console panels.

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In Script tab you can see the written Javascript code.

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In Console tab you can call JavaScript functions and see their results.

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Let’s do an example. In our example page as you see below calculation is done by “Calculate()” function. If we click “9” and then click “+” and then click “3” and at last step call “Calculate()” function on Console tab, we will get the “12” as a result.

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Now, let’s do this example with Selenium JavascriptExecutor.

Test Scenario

  1. Go to http://www.anaesthetist.com/mnm/javascript/calc.htm
  2. Click “9”
  3. Click “+”
  4. Click “3”
  5. Declare JavascriptExecutor and Call Calculate() method.
  6. Assert that result is 12

Test Code:

Execute JavaScript with executeScript() Method

JavascriptExecutor interface comprises of executeScript() method that executes JavaScript in the context of the currently selected frame or window.
Within the script, use document to refer to the current document. Local variables will not be available once the script has finished executing, though global variables will persist.

[1]
If the script has a return value (i.e. if the script contains a return statement), then the following steps will be taken: [1]
•    For an HTML element, this method returns a WebElement
•    For a decimal, a Double is returned
•    For a non-decimal number, a Long is returned
•    For a boolean, a Boolean is returned
•    For all other cases, a String is returned.
•    For an array, return a List<Object> with each object following the rules above. We support nested lists.
•    Unless the value is null or there is no return value, in which null is returned.

Arguments must be a number, a boolean, a String, WebElement, or a list of any combination of the above. An exception will be thrown if the arguments do not meet these criteria. [1]

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I want to give extra examples that shows you what can you do with JavascriptExecutor.

Alert Pop window

Get Page Title

Refresh Browser Window

Scroll-Down Until an Element Displayed

Highlight an Element

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Hide and Show an Element

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Create an Anonymous Function and add it to the Global Window

Navigate to Other Page

» Source Code of All Examples for executeScript() Method «

Execute JavaScript with executeAsyncScript() Method

JavascriptExecutor interface comprises of executeAsyncScript() method that is called an additional final argument “arguments[arguments.lenght-1];” which is a callback function to signal that async execution has finished. We have to call from JavaScript, to tell Webdriver, that our Asynchronous execution has finished. If we do not do that, then executeAsyncScpript will timeout and throw a timeout exception.

The first argument passed to the callback function will be used as the script’s result. This value will be handled as follows: [1]

  • For an HTML element, this method returns a WebElement
  • For a number, a Long is returned
  • For a boolean, a Boolean is returned
  • For all other cases, a String is returned.
  • For an array, return a List<Object> with each object following the rules above. We support nested lists.
  • Unless the value is null or there is no return value, in which null is returned

Before we execute AsyncScript, we have to make sure to set the script timeout. Its default is 0. If we do not set a script timeout, our executeAsyncScript will immediately timeout and it won’t work.

Make sure you set the script timeout before you call it.

I want to show you two examples for AsyncScript. One of them is sleep browser for 4 seconds (4000 milliseconds). The second one is about injecting XMLHttpRequest and wait for the result.

First Example: Performing a sleep in the browser under test.

Test Scenario:

  • First I will get the start time before waiting 4 seconds by using executeAsyncScript() method.
  • Then, I will use executeAsyncScript() to wait 4 seconds.
  • Then, I will get the current time
  • I will subtract (current time – start time) = passed time
  • Assert that passed time is greater than 4 seconds.

Test Code:

Console Output:

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Second Example: Injecting a XMLHttpRequest with POST Method

Our test site is: http://phppot.com/demo/jquery-dependent-dropdown-list-countries-and-states/

It contains a getState(val) function to gather cities according to the country parameter.

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Before selecting country lets open Firefox or Chrome’s network tab and then select “USA” as a country.
Then you will see the POST request details as shown below:

Headers:
You can see the all details about headers as shown below.

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Post:
Then click the POST tab to see parameters that we send by POST method. In this example our parameter is “country_id” and its value is “5”.

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Response:
In this tab, you can see the response of the POST method.

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Now it is time to test below scenario.

  1. Select USA as a country.
  2. Use executeAsyncScript() method to wait callback function executed. It signals that async execution has finished.
  3. Assert that response contains “New York”

Test Code:

Console Output:

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References

[1] https://seleniumhq.github.io/selenium/docs/api/java/org/openqa/selenium/JavascriptExecutor.html