test javascript

Javascript, a programming language available to all web browsers, is an essential tool for interactive and innovative web development. Learning how to test Javascript effectively is equally important to mastering the syntax of the language.

Code snippet for a Simple Javascript Test

In this section, we’re going to start off with illustrating a simple Javascript code snippet for testing. This test will focus on ensuring that a function behaves as expected.

 function addTwoNumbers(a, b) {
    return a + b;
}

module.exports = addTwoNumbers;

const addTwoNumbers = require('./addTwoNumbers');

test('adds 1 + 2 to equal 3', () => {
  expect(addTwoNumbers(1, 2)).toBe(3);
});

In this Javascript code snippet, we have a simple function that adds two numbers. We then export this function to use it in our test. The test code checks if the function correctly adds up 1 and 2 to give 3.

Code Explanation for a Simple Javascript Test

At the beginning of our code, we declare a function titled ‘addTwoNumbers.’ This function will simply return the sum of two numbers. Next, we export our function for future use in our test. Using ‘module.exports,’ we’re ensuring that other files, such as our test file, can import and utilize this function.

Then we import the function into our test file with the ‘require’ command. After the function has been imported, it’s time to define our test. The ‘test’ is a function provided by Jest, a Javascript testing library.

In the ‘test’ function, the first parameter is a string that defines what the test is for (in this case, “adds 1 + 2 to equal 3”). The second parameter is a function that holds the actual testing code. We use ‘expect’ and ‘toBe’ to declare what we expect the function addTwoNumbers(1, 2) to return. In this case, we expect the result to be 3.

If the function behaves as expected, and 1 + 2 does indeed equal 3, the test will pass. If the function returns anything other than 3, the test will fail, alerting us to a problem in our function. This simple, yet effective, way of testing helps ensure that individual parts of your Javascript code are working as intended, leading to overall smoother and more reliable web development.