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What do Test Automation Engineers need to know about JavaScript?

Dzmitry Prakapuk, Software Testing Team Leader, explained why JavaScript is so popular with Test Automation Engineers, what the features of the language are, and what the advantages of its tools are.

Software Testing Team Leader Dzmitry Prakapuk

What you need to know about JavaScript

— Each programming language used to automate testing has its own characteristics. JavaScript is no exception.

  • JavaScript is a dynamically typed language. In dynamic typing, you can omit the definition of data types for variables, it is performed automatically during program execution unlike static typing when data types for variables must be defined before the program is executed. With dynamic typing, the code is faster to write but you may miss errors and they will be harder to locate.
  • JavaScript is a multi-paradigm language: it supports both functional and object-oriented programming styles. As part of automated testing, the multi-paradigm aspect of JavaScript provides flexibility in building the project architecture, and the ability to write tests easily and quickly.
  • JavaScript has the largest package infrastructure for languages. If you need to work with PDF, XLS, or other files as part of tests, for example, JavaScript already has a package that will help you test any file format.

Advantages of JavaScript automation tools

Selenium WebDriver initialization

— Selenium WebDriver is a tool for automating web browser actions. To work with Selenium WebDriver, it needs to be initialized— that is, declared — before it can be used. You need to declare it correctly. Different approaches, in the form of design patterns, are used.

In JavaScript tools, we do not need to initialize Selenium WebDriver and then choose which approach to use. The developers of JavaScript tools considered previous experiences and implemented initialization of the driver for us. In other languages, we need to declare Selenium WebDriver ourselves. This takes time, and it can be hard for a beginner automation engineer to do it correctly.

Wide range of choices

— An especially good example of this is in the area of UI automation, where 3 approaches with JavaScript tools can be used:

  1. Selenium based. A classic approach for automating web applications in which we communicate with the browser (Chrome, Firefox) via Selenium WebDriver.
  2. DevTools Protocol based. This is a newer approach in which we communicate with the browser via DevTool, rather than Selenium WebDriver.
  3. JavaScript based. In this approach, we communicate with the browser via JavaScript-implemented functionality.

Technical capabilities

— Automation does not stand still. With the development of frontend technologies in testing, it became necessary to work with the browser's Network Tab to perform high-quality checks of the application's performance. In JavaScript, it is possible to work with the browser's Network Tab without connecting additional libraries (this is the time to search, study the connection). This option is not available in Java, C#, or Python tools.

Low entry requirements

— To start writing autotests in JavaScript, it is sufficient to:

  • Be able to search for locators. A locator is a string that allows you to find an element (button, input field) on a page of a web application or website.
  • Know the basics of JavaScript. This includes data types, conditional expressions, working with functions, arrays, and loops.
  • Know Page Object. Page Object is a basic approach for organizing an automation project (test framework).
8 useful sources for learning JavaScript

JavaScript is the frontend language

— If you have a web project, the developers will definitely know JavaScript and will help organize the infrastructure of the test framework, create a review, write tests.

Infrastructure for development

— The JavaScript environment is the fastest growing of all. Therefore, there is a high degree of probability that, when you are performing tasks, you will be able to find and use a ready-made package. There are already more than 1.3 million of them in the JavaScript environment.

Where are JavaScript tools used?

  • In the automation of web applications. It is used for emulations of user actions in the browser. For example, you can automatically test the application login form and other more complex cases.
  • In the automation of services. All applications have services that implement the basic logic of the application. JavaScript tools make it possible to start automating services quickly.
  • In the automation of desktop applications written using Electron technology. The most famous applications written in Electron are Skype and Visual Studio Code. JavaScript has tools to test the visual part as well as the application itself.
  • In the automation of mobile applications. More and more mobile applications will be developed, so mobile automation is a significant trend. With JavaScript tools, you can automate both Android and iOS applications.

Our thanks to our partner site training.epam.com.