Vanilla JavaScript String to Number


Three different ways to convert a String into a number

4 Aug, 2020 · 2 min read

Sometimes we want to convert a number to a string; in my latest code piece, a limit was set on a data attribute. This comes true as a string, so how do we convert this to a number in JavaScript?

In this case, there are not one but three valid and supported methods of converting our string to a number.

  • Number
  • parseInt
  • parseFloat

JavaScript Number Method

Number is a generic way of converting. It’s the stricter check. Here are some examples with outputs:

<!-- Number -->
console.log(Number(`1337`)); // 1337
console.log(Number(`13.37`)); // 13.37
console.log(Number(`13leet37`)); // NaN
console.log(Number(`13,37`)); // NaN

As you can see, it works on actual numbers, but as soon as we use other characters or a comma, it won’t work.

JavaScript ParseInt Method

ParseInt converts our string into an integer non-rounded. It has two arguments, the input and the radix, which is the base number. For us, the default is 10

<!-- ParseInt -->
const text1 = '1337';
const text2 = '13.37';
const text3 = '13leet37';
const text4 = '13,37';
console.log(parseInt(text1, 10)); // 1337
console.log(parseInt(text2, 10)); // 13
console.log(parseInt(text3, 10)); // 13
console.log(parseInt(text4, 10)); // 13

The downside can be it’s rounding everything, so let’s look at ParseFloat.

JavaScript ParseFloat Method

As mentioned, the parseFloat is used to return stuff with decimals.

<!-- ParseFloat -->
const text1 = '1337';
const text2 = '13.37';
const text3 = '13.3leet37';
const text4 = '13,37';
console.log(parseFloat(text1, 10)); // 13.37
console.log(parseFloat(text2, 10)); // 13
console.log(parseFloat(text3, 10)); // 13.3
console.log(parseFloat(text4, 10)); // 13

Very cool method!

See all these in action on Codepen.

See the Pen Vanilla JavaScript String to Number by Chris Bongers (@rebelchris) on CodePen.

Thank you for reading, and let’s connect!

Thank you for reading my blog. Feel free to subscribe to my email newsletter and connect on Facebook or Twitter

Spread the knowledge with fellow developers on Twitter
Tweet this tip
Powered by Webmentions - Learn more

Read next 📖

Removing all vowels with JavaScript

3 Dec, 2022 · 2 min read

Removing all vowels with JavaScript

10 games to learn JavaScript

2 Dec, 2022 · 3 min read

10 games to learn JavaScript

Join 2099 devs and subscribe to my newsletter