Extract a Number from a String with JavaScript

By  on  

User input from HTML form fields is generally provided to JavaScript as a string. We've lived with that fact for decades but sometimes developers need to extract numbers from that string. There are multiple ways to get those numbers but let's rely on regular expressions to extract those numbers!

To employ a regular expression to get a number within a string, we can use \d+:

const string = "x12345david";
const [match] = string.match(/(\d+)/);
match; // 12345

Regular expressions are capable of really powerful operations within JavaScript; this practice is one of the easier operations. Converting the number using a Number() wrapper will give you the number as a Number type.

Recent Features

Incredible Demos

  • By
    Drag and Drop Z-Index Stacking

    In an example for a previous post, I showed you how to use opacity during a drag'n'drop transaction. One bit I didn't account for was element stacking and bringing the most recent element to the top of the stack. To do...

  • By
    Create a CSS Cube

    CSS cubes really showcase what CSS has become over the years, evolving from simple color and dimension directives to a language capable of creating deep, creative visuals.  Add animation and you've got something really neat.  Unfortunately each CSS cube tutorial I've read is a bit...

Discussion

  1. Dekel

    the code string.match(/(\d+)/); assumes that a match is found. If no number is present in the string, string.match(/(\d+)/) will return null, and attempting to destructure null will result in an error

Wrap your code in <pre class="{language}"></pre> tags, link to a GitHub gist, JSFiddle fiddle, or CodePen pen to embed!