JavascriptExecutor in Selenium Complete Guide

JavascriptExecutor in Selenium is very crucial when you are having some problems while using Selenium built-in methods. Sometimes we cannot handle some conditions or problems with Webdriver, web controls don’t react well against selenium commands. In these kinds of situations, we use the JavascriptExecutor Selenium interface.

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 the Selenium JavascriptExecutor interface which executes JavaScript through the Selenium Webdriver instance. It has executeScript and executeAsyncScript methods, to run JavaScript on the current browser.

JavascriptExecutor in Selenium

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 in Javascript.

First of all, let’s open Chrome developer tools then click the source tab. You will see the JavaScript codes.

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

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 the last step call “Calculate()” function on the Console tab, we will get the “12” as a result.

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:

@TestInstance(TestInstance.Lifecycle.PER_CLASS)
@TestMethodOrder(MethodOrderer.MethodName.class)
public class Alerts {
    private WebDriver driver;
    private String url = "http://www.anaesthetist.com/mnm/javascript/calc.htm";
    
    @BeforeAll
    public void setupTest() {
        driver = new ChromeDriver();
        driver.navigate().to(url);
        driver.manage().window().maximize();
    }

    @Test
    public void T01_calculatorJavaScriptTest() {
        //1-) Click "9"
        driver.findElement(By.name("nine")).click();

        //2-) Click "+"
        driver.findElement(By.name("add")).click();

        //3-) Click "3"
        driver.findElement(By.name("three")).click();

        //4-) Declare JavaScriptExecutor and call "Calculate()" function
        JavascriptExecutor js =(JavascriptExecutor)driver;
        js.executeScript("Calculate();");

        //5-) Assert that result is 12
        WebElement result = driver.findElement(By.name("Display"));
        Assertions.assertEquals("12", result.getAttribute("value"));
    }

    @AfterAll
    public void quitDriver() {
        driver.quit();
    }
}

Execute JavaScript with executeScript()

JavascriptExecutor interface comprises of executeScript() method that executes JavaScript in the context of the currently selected frame or window. Within the script, use the 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:

•    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]

I want to share with you more examples that show us what can we do with JavascriptExecutor.

Alert Pop window

JavascriptExecutor js =(JavascriptExecutor)driver;
js.executeScript("alert('SW Test Academy!');");
driver.switchTo().alert().accept();

Get Page Title

JavascriptExecutor js =(JavascriptExecutor)driver;
String title = js.executeScript("return document.title;").toString();
assertThat(driver.getTitle(), is(title));

Refresh Browser Window

JavascriptExecutor js =(JavascriptExecutor)driver;
js.executeScript("history.go(0);");

Scroll-Down Until an Element Displayed

WebElement twelfthArticle = driver.findElement(By.xpath("//article[12]"));
js.executeScript("arguments[0].scrollIntoView(true);", twelfthArticle);

Highlight an Element

WebElement secondArticle = driver.findElement(By.xpath("//article[2]"));
js.executeScript("arguments[0].style.border='3px dotted blue'", secondArticle);

Hide and Show an Element

//JS hide an element
js.executeScript("document.querySelector('article:nth-of-type(2)').style.display='none'");
//JS show an element
js.executeScript("document.querySelector('article:nth-of-type(2)').style.display='block'");

Javascriptexecutor Click

WebElement searchBox = driver.findElement(By.cssSelector("form > label > input"));
js.executeScript("arguments[0].click();", searchBox);

Type text using Javascriptexecutor

WebElement searchBox = driver.findElement(By.cssSelector("form > label > input"));
js.executeScript("document.querySelector('form > label > input').value = 'SW Test Academy'");

Navigate to Other Page

js.executeScript("window.location = 'https:/'");

Create an Anonymous Function and add it to the Global Window

@Test
public void T03_createAnAnonymousFunction() {
    driver.navigate().to("https:");

    //Create an anonymous function
    //Change title with JavascriptExecutor
    js.executeScript("document.title='Title is changed manually!';");
    Assertions.assertEquals("Title is changed manually!", driver.getTitle());

    //Create an anonymous function that will stored and added into the global window
    js.executeScript("window.changeTitle = function(){document.title='Title is changed by function!';};" +
        "window.changeTitle.call();");
    Assertions.assertEquals("Title is changed by function!", driver.getTitle());

    //Change title manually
    js.executeScript("document.title='Title is changed manually!';");
    Assertions.assertEquals("Title is changed manually!", driver.getTitle());

    //Change title with Function
    js.executeScript("window.changeTitle.call();");
    Assertions.assertEquals("Title is changed by function!", driver.getTitle());
}

Source Code of All Examples for executeScript()

@TestInstance(TestInstance.Lifecycle.PER_CLASS)
@TestMethodOrder(MethodOrderer.MethodName.class)
public class ExecuteJavascriptExamples {
    private WebDriver          driver;
    private WebDriverWait      wait;
    private JavascriptExecutor js;

    @BeforeAll
    public void setupTest() {
        WebDriverManager.chromedriver().setup();
        driver = new ChromeDriver();
        wait = new WebDriverWait(driver, Duration.ofSeconds(10));
        js = (JavascriptExecutor) driver;
    }

    @Test
    public void T01_calculatorJavaScriptTest() {
        driver.navigate().to("http://www.anaesthetist.com/mnm/javascript/calc.htm");
        driver.manage().window().maximize();
        //1-) Click "9"
        driver.findElement(By.name("nine")).click();

        //2-) Click "+"
        driver.findElement(By.name("add")).click();

        //3-) Click "3"
        driver.findElement(By.name("three")).click();

        //4-) Declare JavaScriptExecutor and call "Calculate()" function
        js.executeScript("Calculate();");

        //5-) Assert that result is 12
        WebElement result = driver.findElement(By.name("Display"));
        Assertions.assertEquals("12", result.getAttribute("value"));
    }

    @Test
    @SneakyThrows
    public void T02_jsExamples() {
        driver.navigate().to("https:");

        //JS alert
        js.executeScript("alert('SW Test Academy!');");
        driver.switchTo().alert().accept();
        Thread.sleep(1000);

        //JS get title
        String title = js.executeScript("return document.title;").toString();
        Assertions.assertEquals(title, driver.getTitle());
        Thread.sleep(1000);

        //JS Refresh
        JavascriptExecutor js = (JavascriptExecutor) driver;
        js.executeScript("history.go(0);");
        Thread.sleep(1000);

        //Goto Blog Page
        ExpectedConditions.visibilityOfElementLocated(By.xpath("//div//ul//li//a[contains(@href, 'blog')]")).apply(driver).click();

        //JS Scroll
        WebElement secondArticle = driver.findElement(By.cssSelector("article:nth-of-type(2)"));
        WebElement twelfthArticle = driver.findElement(By.xpath("//article[12]"));
        js.executeScript("arguments[0].scrollIntoView(true);", twelfthArticle);
        Thread.sleep(1000);
        js.executeScript("arguments[0].scrollIntoView(true);", secondArticle);

        //JS Highlight
        js.executeScript("arguments[0].style.border='3px dotted blue'", secondArticle);
        Thread.sleep(1000);

        //JS hide an element
        js.executeScript("document.querySelector('article:nth-of-type(2)').style.display='none'");
        Thread.sleep(1000);

        //JS show an element
        js.executeScript("document.querySelector('article:nth-of-type(2)').style.display='block'");
        Thread.sleep(1000);

        //JS click and type text
        WebElement logo = driver.findElement(By.cssSelector(".header-image.is-logo-image"));
        WebElement searchBox = driver.findElement(By.cssSelector("form > label > input"));
        js.executeScript("arguments[0].scrollIntoView(true);", logo);
        js.executeScript("arguments[0].click();", searchBox);
        js.executeScript("document.querySelector('form > label > input').value = 'SW Test Academy'");
        Thread.sleep(3000);

        //JS Navigate to Other Page
        js.executeScript("window.location = 'https:/'");
        Thread.sleep(1000);
    }

    @Test
    public void T03_createAnAnonymousFunction() {
        driver.navigate().to("https:");

        //Create an anonymous function
        //Change title with JavascriptExecutor
        js.executeScript("document.title='Title is changed manually!';");
        Assertions.assertEquals("Title is changed manually!", driver.getTitle());

        //Create an anonymous function that will stored and added into the global window
        js.executeScript("window.changeTitle = function(){document.title='Title is changed by function!';};" +
            "window.changeTitle.call();");
        Assertions.assertEquals("Title is changed by function!", driver.getTitle());

        //Change title manually
        js.executeScript("document.title='Title is changed manually!';");
        Assertions.assertEquals("Title is changed manually!", driver.getTitle());

        //Change title with Function
        js.executeScript("window.changeTitle.call();");
        Assertions.assertEquals("Title is changed by function!", driver.getTitle());
    }

    @AfterAll
    public void quitDriver() {
        driver.quit();
    }
}

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 of AsyncScript. One of them is “sleep browser for 4 seconds” (4000 milliseconds). The second one is about injecting XMLHttpRequest and waiting for the result.

First Example: Performing sleep in the browser under test.

Test Scenario:

• First I will get the start time before waiting 4 seconds by using the 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 the passed time is greater than 4 seconds.

Test Code:

@TestInstance(TestInstance.Lifecycle.PER_CLASS)
@TestMethodOrder(MethodOrderer.MethodName.class)
public class ExecuteAsyncJavascriptExamples {
    private        WebDriver          driver;
    private static String             url = "http://phppot.com/demo/jquery-dependent-dropdown-list-countries-and-states/";
    private        JavascriptExecutor js;

    @BeforeAll
    public void setupTest() {
        WebDriverManager.chromedriver().setup();
        driver = new ChromeDriver();
        js = (JavascriptExecutor) driver;
        driver.navigate().to(url);
    }

    @Test
    public void T01_browserSleepExampleTest() {
        //Set ScriptTimeout
        driver.manage().timeouts().scriptTimeout(Duration.ofSeconds(10));

        //Declare and set start time
        long startTime = System.currentTimeMillis();

        //Call executeAsyncScript() method
        js.executeAsyncScript("window.setTimeout(arguments[arguments.length - 1], 4000);");

        //Get the difference (currentTime - startTime) it should be greater than 1500
        System.out.println("Passed time: " + (System.currentTimeMillis() - startTime));

        //Assert that the time difference is greater than 4000
        Assertions.assertTrue((System.currentTimeMillis() - startTime) > 4000,
            "Time difference must be greater than 4000 milliseconds");
    }

    @AfterAll
    public void quitDriver() {
        driver.quit();
    }
}

Console Output:

Second Example: Injecting an 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.

Before selecting a country let’s 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.

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

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

Now it is time to test the below scenario.

1. Select the 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:

@TestInstance(TestInstance.Lifecycle.PER_CLASS)
@TestMethodOrder(MethodOrderer.MethodName.class)
public class ExecuteAsyncJavascriptExamples {
    private        WebDriver          driver;
    private static String             url = "http://phppot.com/demo/jquery-dependent-dropdown-list-countries-and-states/";
    private        JavascriptExecutor js;

    @BeforeAll
    public void setupTest() {
        WebDriverManager.chromedriver().setup();
        driver = new ChromeDriver();
        js = (JavascriptExecutor) driver;
        driver.navigate().to(url);
    }

@Test
public void T02_sendXMLHTTPRequestTest() {
    Object response = null;

    //Set ScriptTimeout
    driver.manage().timeouts().scriptTimeout(Duration.ofSeconds(10));

    //Declare JavascriptExecutor
    JavascriptExecutor js = (JavascriptExecutor) driver;

    //Injecting a XMLHttpRequest and waiting for the result
    //Ref1: https://seleniumhq.github.io/selenium/docs/api/java/org/openqa/selenium/JavascriptExecutor.html
    //Ref2: http://www.openjs.com/articles/ajax_xmlhttp_using_post.php
    try {
        response = js.executeAsyncScript(
            //Declare callback first!
            "var callback = arguments[arguments.length - 1];" +

                //Declare url, parameters and method for POST
                //Send country_id=5 (USA)
                "var http = new XMLHttpRequest();" +
                "var url = 'get_state.php';" +  //url
                "var params = 'country_id=5';" +  //parameters
                "http.open('POST', url, true);" +

                //Send the proper header information along with the request
                "http.setRequestHeader('Content-type', 'application/x-www-form-urlencoded');" +
                "http.setRequestHeader('Content-length', params.length);" +
                "http.setRequestHeader('Connection', 'close');" +

                //Call a function when the state changes.
                "http.onreadystatechange = function() {" +
                "    if(http.readyState == 4) {" +
                "        callback(http.responseText);" +
                "    };" +
                "};" +
                "http.send(params);");
    }
    catch (UnhandledAlertException e) {
        System.err.println("Error Occurred!");
    }

    //Assert that returned cities are related with USA
    System.out.println((String) response);
    Assertions.assertTrue(((String) response).contains("<option value=\"4\">New York</option>"));
}

    @AfterAll
    public void quitDriver() {
        driver.quit();
    }
}

Console Output:

Other JavascriptExecutor in Selenium Articles

You can also check my Selenium Webdriver wait for JavaScript JQuery and Angular article to learn how to wait for Asynchronous calls in your test automation codes.

How to handle javascript alerts with javascriptexecutor in selenium: https:/javascript-alert-javascriptexecutor-selenium/

Github Project

https://github.com/swtestacademy/selenium-examples/tree/main/src/test/java/javascript

Thanks.
Onur Baskirt

Onur Baskirt

Onur Baskirt is a Software Engineering Leader with international experience in world-class companies. Now, he is a Software Engineering Lead at Emirates Airlines in Dubai.