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

  • 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...

  • By
    Chris Coyier’s Favorite CodePen Demos

    David asked me if I'd be up for a guest post picking out some of my favorite Pens from CodePen. A daunting task! There are so many! I managed to pick a few though that have blown me away over the past few months. If you...

Incredible Demos

  • By
    MooTools CountDown Plugin

    There are numerous websites around the internet, RapidShare for example, that make you wait an allotted amount of time before presenting you with your reward. Using MooTools, I've created a CountDown plugin that allows you to easily implement a similar system. The MooTools JavaScript The CountDown class...

  • By
    Form Element AJAX Spinner Attachment Using MooTools

    Many times you'll see a form dynamically change available values based on the value of a form field. For example, a "State" field will change based on which Country a user selects. What annoys me about these forms is that they'll often do an...

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!