Selenium Webdriver 在当前浏览器 Context 中 执行 JS 脚本。 Execute JavaScript based code using Selenium Webdriver

2019-02-22 15:09:08 浏览数 (1)

In Selenium Webdriver, locators like XPath, CSS, etc. are used to identify and perform operations on a web page.

In case, these locators do not work you can use JavaScriptExecutor. You can use JavaScriptExecutor to perform an desired operation on a web element.

Selenium support javaScriptExecutor. There is no need for an extra plugin or add-on. You just need to import (org.openqa.selenium.JavascriptExecutor) in the script as to use JavaScriptExecutor .

We will discuss JavaScriptExecutor and its execution in Selenium Webdriver in this tutorial.

In this tutorial, you will learn -

  • What is JavaScriptExecutor
  • Example demonstrating various operations performed by JavaScriptExecutor

What is JavaScriptExecutor

JavaScriptExecutor is an Interface that helps to execute JavaScript through Selenium Webdriver.

JavaScriptExecutor provides two methods "executescript" & "executeAsyncScript"

to run javascript on the selected window or current page.

image.png

  1. executeAsyncScript

With Asynchronous script, your page renders more quickly. Instead of forcing users to wait for a script to download before the page renders. This function will execute an asynchronous piece of JavaScript in the context of the currently selected frame or window in Selenium. The JS so executed is single-threaded with a various callback function which runs synchronously.

  1. executeScript

This method executes JavaScript in the context of the currently selected frame or window in Selenium. The script used in this method runs in the body of an anonymous function (a function without a name). We can also pass complicated arguments to it.

The script can return values. Data types returned are

  • Boolean
  • Long
  • String
  • List
  • WebElement.

The basic syntax for JavascriptExecutor is given below:

Syntax:

代码语言：javascript复制
js.executeScript(Script,Arguments);
  • Script – This is the JavaScript that needs to execute.
  • Arguments – It is the arguments to the script. It's optional.

Example demonstrating various operations performed by JavaScriptExecutor

Example of executeAsyncScript

Using the executeAsyncScript, helps to improve the performance of your test. It allows writing test more like a normal coding.

The execSync blocks further actions being performed by the Selenium browser but execAsync does not block action. It will send a callback to the server-side Testing suite once the script is done. It means everything inside the script will be executed by the browser and not the server.

Example: Performing a sleep in the browser under test.

In this scenario, we will use "Guru99" demo site to illustrate executeAsyncScript. In this example, you will

  • Launch the browser.
  • Open site "http://demo.guru99.com/V4/ ".
  • Application waits for 5 sec to perform a further action.

Step 1) Capture the start time before waiting for 5 seconds ( 5000 milliseconds) by using executeAsyncScript() method.

Step 2) Then, use executeAsyncScript() to wait 5 seconds.

Step 3) Then, get the current time.

**Step 4) **Subtract (current time – start time) = passed time.

Step 5) Verify the output it should display more than 5000 milliseconds

代码语言：javascript复制
import java.util.concurrent.TimeUnit;       

import org.openqa.selenium.JavascriptExecutor;      
import org.openqa.selenium.WebDriver;       
import org.openqa.selenium.firefox.FirefoxDriver;       
import org.testng.annotations.Test;     

public class JavaSE_Test {              

    @Test       
    public void Login()                     
    {       

        WebDriver driver= new FirefoxDriver();          

        //Creating the JavascriptExecutor interface object by Type casting      
        JavascriptExecutor js = (JavascriptExecutor)driver;     

        //Launching the Site.       
        driver.get("http://demo.guru99.com/V4/");           

          //Maximize window     
          driver.manage().window().maximize();      

          //Set the Script Timeout to 20 seconds        
          driver.manage().timeouts().setScriptTimeout(20, TimeUnit.SECONDS);            

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

          //Call executeAsyncScript() method to wait for 5 seconds      
          js.executeAsyncScript("window.setTimeout(arguments[arguments.length - 1], 5000);");           

         //Get the difference (currentTime - startTime)  of times.      
         System.out.println("Passed time: "   (System.currentTimeMillis() - start_time));                   

    }       
}

Output: Successfully displayed the passed time more than 5 seconds(5000 miliseconds) as shown below:

代码语言：javascript复制
[TestNG] Running:

C:UsersgauravnAppDataLocalTemptestng-eclipse-387352559testng-customsuite.xml

log4j:WARN No appenders could be found for logger (org.apache.http.client.protocol.RequestAddCookies).

log4j:WARN Please initialize the log4j system properly.

log4j:WARN See http://logging.apache.org/log4j/1.2/faq.html#noconfig for more info.

Passed time: 5022

PASSED: Login

===============================================

Default test

Tests run: 1, Failures: 0, Skips: 0

===============================================

Example of executeScript

For executeScript, we will see three different example one by one.

1) Example: Click a button to login and generate Alert window using JavaScriptExecutor.

In this scenario, we will use "Guru99" demo site to illustrate JavaScriptExecutor. In this example,

  • Launch the web browser
  • open the site "http://demo.guru99.com/V4/ "and
  • login with credentials

image.png

  • Display alert window on successful login.
代码语言：javascript复制
import org.openqa.selenium.By;      
import org.openqa.selenium.JavascriptExecutor;      
import org.openqa.selenium.WebDriver;       
import org.openqa.selenium.WebElement;      
import org.openqa.selenium.firefox.FirefoxDriver;       
import org.testng.annotations.Test;     

public class JavaSE_Test {              

    @Test       
    public void Login()                     
    {       
        WebDriver driver= new FirefoxDriver();          

        //Creating the JavascriptExecutor interface object by Type casting      
        JavascriptExecutor js = (JavascriptExecutor)driver;     

        //Launching the Site.       
        driver.get("http://demo.guru99.com/V4/");           

        WebElement button =driver.findElement(By.name("btnLogin"));         

        //Login to Guru99       
        driver.findElement(By.name("uid")).sendKeys("mngr34926");                   
        driver.findElement(By.name("password")).sendKeys("amUpenu");                    

        //Perform Click on LOGIN button using JavascriptExecutor        
        js.executeScript("arguments[0].click();", button);

        //To generate Alert window using JavascriptExecutor. Display the alert message          
        js.executeScript("alert('Welcome to Guru99');");   

    }       
}

Output: When the code is executed successfully. You will observe

  • Successful click on login button and the
  • Alert window will be displayed (see image below).

Execute JavaScript based code using Selenium Webdriver

2) Example: Capture Scrape Data and Navigate to different pages using JavaScriptExecutor.

Execute the below selenium script. In this example,

  • Launch the site
  • Fetch the details of the site like URL of the site, title name and domain name of the site.
  • Then navigate to a different page.
代码语言：javascript复制
import org.openqa.selenium.JavascriptExecutor;      
import org.openqa.selenium.WebDriver;       
import org.openqa.selenium.firefox.FirefoxDriver;       
import org.testng.annotations.Test;     

public class JavaSE_Test {              

    @Test       
    public void Login()                     
    {       
        WebDriver driver= new FirefoxDriver();          

        //Creating the JavascriptExecutor interface object by Type casting      
        JavascriptExecutor js = (JavascriptExecutor)driver;     

        //Launching the Site.       
        driver.get("http://demo.guru99.com/V4/");

        //Fetching the Domain Name of the site. Tostring() change object to name.       
        String DomainName = js.executeScript("return document.domain;").toString();         
        System.out.println("Domain name of the site = " DomainName);                    

        //Fetching the URL of the site. Tostring() change object to name        
        String url = js.executeScript("return document.URL;").toString();           
        System.out.println("URL of the site = " url);                   

       //Method document.title fetch the Title name of the site. Tostring() change object to name       
       String TitleName = js.executeScript("return document.title;").toString();            
       System.out.println("Title of the page = " TitleName);                    

      //Navigate to new Page i.e to generate access page. (launch new url)      
      js.executeScript("window.location = 'http://demo.guru99.com/'");          
    }       
}

Output: When above code is executed successfully, it will it will fetch the details of the site and navigate to different page as shown below.

Execute JavaScript based code using Selenium Webdriver

代码语言：javascript复制
[TestNG] Running:

C:UsersgauravnAppDataLocalTemptestng-eclipse-467151014testng-customsuite.xml

log4j:WARN No appenders could be found for logger (org.apache.http.client.protocol.RequestAddCookies).

log4j:WARN Please initialize the log4j system properly.

log4j:WARN See http://logging.apache.org/log4j/1.2/faq.html#noconfig for more info.

Domain name of the site = demo.guru99.com

URL of the site = http://demo.guru99.com/V4/

Title of the page = Guru99 Bank Home Page

PASSED: Login

===============================================

Default test

Tests run: 1, Failures: 0, Skips: 0

===============================================

image.png

3) Example: Scroll Down using JavaScriptExecutor.

Execute the below selenium script. In this example,

  • Launch the site
  • Scroll down by 600 pixel
代码语言：javascript复制
import org.openqa.selenium.JavascriptExecutor;      
import org.openqa.selenium.WebDriver;       
import org.openqa.selenium.firefox.FirefoxDriver;       
import org.testng.annotations.Test;     

public class JavaSE_Test {              

    @Test       
    public void Login()                     
    {       
        WebDriver driver= new FirefoxDriver();          

        //Creating the JavascriptExecutor interface object by Type casting      
        JavascriptExecutor js = (JavascriptExecutor)driver;     

        //Launching the Site.       
        driver.get("http://moneyboats.com/");           

        //Maximize window       
        driver.manage().window().maximize();        

        //Vertical scroll down by 600  pixels       
        js.executeScript("window.scrollBy(0,600)");         
    }       
}

Output: When above code is executed, it will scroll down by 600 pixels (see image below).

image.png

Summary:

JavaScriptExecutor is used when Selenium Webdriver fails to click on any element due to some issue.

  • JavaScriptExecutor provides two methods "executescript" & "executeAsyncScript" to handle.
  • Executed the JavaScript using Selenium Webdriver.
  • Illustrated how to click on an element through JavaScriptExecutor, if selenium fails to click on element due to some issue.
  • Generated the 'Alert' window using JavaScriptExecutor.
  • Navigated to the different page using JavaScriptExecutor.
  • Scrolled down the window using JavaScriptExecutor.
  • Fetched URL, title, and domain name using JavaScriptExecutor.

https://www.guru99.com/execute-javascript-selenium-webdriver.html

node.js javascript selenium

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