how to find the first number from string in js(javascript)?-CodePudding

How to find the first number from string in javascript?

var string = "120-250";
var string = "120,250";
var string = "120 | 250";

CodePudding user response：

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

CodePudding user response：

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"));