Author: John Au-Yeung

Sometimes, we want to disable console inside unit tests with Jest.

In this article, we’ll look at how to disable console inside unit tests with Jest.

How to disable console inside unit tests with Jest?

To disable console inside unit tests with Jest, we can use the --silent option or set the console methods to mocked functions.

For instance, we run

jest --silent

to run jest with the --silient to disable console output when running tests.

Or we can create a tests/setup.js file with

global.console = {
  ...console,
  log: jest.fn(),
  debug: jest.fn(),
  info: jest.fn(),
  warn: jest.fn(),
  error: jest.fn(),
};

to set all the console methods to mocked functions.

And then we can use the config by writing

module.exports = {
  verbose: true,
  setupFilesAfterEnv: ["<rootDir>/__tests__/setup.js"],
};

to add tests/setup.js to the setupFilesAfterEnv array in jest.config.js to load that when running tests.

Conclusion

To disable console inside unit tests with Jest, we can use the --silent option or set the console methods to mocked functions.

Sometimes, we want to check if date is a valid one with JavaScript.

In this article, we’ll look at how to check if date is a valid one with JavaScript.

How to check if date is a valid one with JavaScript?

To check if date is a valid one with JavaScript, we can use the moment.js’ isValid function.

For instance, we write

const date = moment("2022-10-19").isValid();

to call moment with a date string.

Then we call isValid to check if the date string is a valid one.

Conclusion

To check if date is a valid one with JavaScript, we can use the moment.js’ isValid function.

Sometimes, we want to get the browser’s scrollbar sizes with JavaScript.

In this article, we’ll look at how to get the browser’s scrollbar sizes with JavaScript.

How to get the browser’s scrollbar sizes with JavaScript?

To get the browser’s scrollbar sizes with JavaScript, we can subtract the window’s width by the html element’s width.

For instance, we write

const scrollBarWidth =
  window.innerWidth - document.getElementsByTagName("html")[0].clientWidth;

to get the window’s width with window.innerWidth.

And then we subtract that by the html element’s width which we get by

document.getElementsByTagName("html")[0].clientWidth

to get the scrollbar’s width.

Conclusion

To get the browser’s scrollbar sizes with JavaScript, we can subtract the window’s width by the html element’s width.

Sometimes, we want to change source on HTML5 video tag with JavaScript.

In this article, we’ll look at how to change source on HTML5 video tag with JavaScript.

How to change source on HTML5 video tag with JavaScript?

To change source on HTML5 video tag with JavaScript, we an set the src property of the video element.

For instance, we write

const changeSource = (url) => {
  const video = document.getElementById("video");
  video.src = url;
  video.play();
};

to define the changeSource function.

In it, we get the video with getElementById.

And then we set the src property of the video element to the url to change the video source.

Conclusion

To change source on HTML5 video tag with JavaScript, we an set the src property of the video element.