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How to find the first number from string in javascript?

var string = "120-250"; var string = "120,250"; var string = "120 | 250";
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  • regular expression, match start of string and numbers Commented Sep 8, 2022 at 14:07
  • Just use parseInt(string). Commented Sep 8, 2022 at 18:38

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Here is an example that may help you understand.

Use the search() method to get the index of the first number in the string.

The search method takes a regular expression and returns the index of the first match in the string.

const str = 'one 2 three 4' const index = str.search(/[0-9]/); console.log(index); // 4 const firstNum = Number(str[index]); console.log(firstNum); // 2
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Basic regular expression start of string followed by numbers /^\d+/

const getStart = str => str.match(/^\d+/)?.[0]; console.log(getStart("123,456")); console.log(getStart("123-456")); console.log(getStart("123|456")); console.log(getStart("xxx,xxx"));

Or parseInt can be used, but it will drop leading zeros.

const getStart = str => parseInt(str, 10); console.log(getStart("123,456")); console.log(getStart("123-456")); console.log(getStart("123|456")); console.log(getStart("xxx,xxx"));

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