A tracer utility in 2kb « JavaScript, JavaScript

Getting a regular expression from a string in JavaScript is quite simple:

new RegExp('Hello Universe');
# => /Hello Universe/

You can also use special characters:

new RegExp('^(\\d+) users')
# => /^(\d+) users/

Our expressi...

This card describes how to pass an array with multiple element to a JavaScript function, so that the first array element becomes the first function argument, the second element becomes the second argument, etc.

Note how this is different from pas...

When you register a delegated event using on (or the deprecated delegate / live), it is somewhat hard to manually trigger these events manually, e.g. for testing.

After trying jQuery's [`...

When is a global variable not a variable? When it is a property of the global object.

You can use this code:

function scrollToLine($textarea, lineNumber) {
  var lineHeight = parseInt($textarea.css('line-height'));
  $textarea.scrollTop(lineNumber * lineHeight);      
}

Some caveats about this code:

1. Your t...

Checking if a JavaScript value is of a given type can be very confusing:

• There are two operators typeof and instanceof which work very differently.
• JavaScript has some primitive types, like string literals, that are not objects (as oppose...

Here is a set of additive color model conversion algorithms that I found published on Wikipedia and have implemented in JavaScript.

Great presentation about writing Javascript like you write everything else: Well-structured and tested.

JavaScript is no longer a toy language. Many of our applications can’t function without it. If we are going to use JavaScript to do real thi...

The goal is to get Jasmine specs running in a Rails project using Webpacker, with the browser based test runner. Should be easily adaptable to a pure Webpack setup.

Step 1: Install Jasmine

yarn...

Using querySelector or querySelectorAll in JavaScript, you can easily find descendants of a node that match a given selector.

But what if you want to find only children (i.e. direct descendants) of an element?
Easy: use :scope. It referen...