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
    QuickBoxes for Dojo

    Adding to my mental portfolio is important to me. First came MooTools, then jQuery, and now Dojo. I speak often with Peter Higgins of Dojo fame and decided it was time to step into his world. I chose a simple but useful plugin...

  • By
    jQuery UI DatePicker:  Disable Specified Days

    One project I'm currently working on requires jQuery. The project also features a datepicker for requesting a visit to their location. jQuery UI's DatePicker plugin was the natural choice and it does a really nice job. One challenge I encountered was the...

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!