5 handy Javascript one-liners — First published on fullweb.io issue #48

5-handy-javascript-one-liners.md

5 handy JavaScript one-liners

1. Generate a random string:

Math.random().toString(36).substr(2); 

This simply generates a random float, casts it into a String using base 36 and remove the 2 first chars 0 and. Note that this is not a replacement for UUID generation.

2. Clone an array:

var newA = myArray.slice(0); 

This will return a copy of the array, ensuring no other variables point to it.

3. Remove HTML tags:

"<b>A</b>".replace(/<[^>]+>/gi, ""); 

This is using a simple regular expression to remove any string that looks like <xxx> where x can be any char, including /.

4. Set a default value:

function foo(opts) {
  var options = opts || {};
} 

You will see this in any decent JS code. If opts is defined and not “binarily” false it will be assigned to options, otherwise it will assign an empty dictionary {}.

5. Reverse a string:

var str = "Pouet this string.";
str.split('').reverse().join('');
// Output: ".gnirts siht teuoP"
// Keep words order with:
str.split(' ').reverse().join(' ');
// Output: "string. this Pouet" 
// The first example splits on every character, reverses them and puts them back together.

The second splits only on words and joins them back separated by a space.

are you from python? {} is not a dictionary, its an object. Also, you should probably add the equivalent es6 versions of your on liners because node now supports most features of es6.

Hi @alphashuro, thanks for your comment! I'm more of a Python developer indeed.

To be pedantic, {} is an object in both languages, JavaScript and Python. And while we often use it to define "classes" in JavaScript, we also quite often use it just as a dictionary, for instance as in the example above, to store options.

These one-liners are meant to be used both in node and in browsers, where the support for ES6 isn't there 100% just yet. That being said, as the support is quite good already I may indeed include ES6 examples is the very near future.

Don't forget the period included in your initial str value of "Pouet this string." in #5. Your outputs would be ".gnirts siht teuoP" and "string. this Pouet" instead.

Hey @joeoravec, thanks for the feedback! I just updated the Gist.

In JavaScript there actually aren't any "classes", {} is actually a real object because at any point you can define functions on a {} that would have a reference to the calling object, were as dictionaries exclusively store key/value pairs. If you have seen the word "class" anywhere its actually just syntatic sugar to hide the prototypal inheritence that happens in the background.

Yes, I have put the word classes between quotes to mean that there are no classes per se in JavaScript.