如何使用 JavaScript 为每两个数字添加空格？

Question

I like to output a formatted number with a space after every two numbers, I've tried this:

 function twoSpaceNumber(num) {
    return num.toString().replace(/\B(?<!\.\d)(?=([0-9]{2})+(?!\d))/g, " ");
}

twoSpaceNumber(12345678) => 1 23 45 67 89 ( should start with 12 ? )

and also when it starts with 0 I had very strange output

twoSpaceNumber(012345678) => 12 34 56 78

Answer 1

Please consider

var s = "1234456";
var t = s.match(/.{1,2}/g);
var u = t.join(" ");
console.log(u);

which logs

12 34 45 6

and

var s = "ABCDEF";
var t = s.match(/.{1,2}/g);
var u = t.join(" ");
console.log(u);

which logs

AB CD EF

Note that s is a string.

Is that what you need?

Answer 2

Pass num as a string, not a number, else the leading zeros will disappear and use

function twoSpaceNumber(num) {
  return num.replace(/\d{2}(?!$)/g, "$& ");
}

The regex matches two digits that are not at the end of string (in order not to add a space at the string end).

JavaScript demo

 const regex = /\\d{2}(?!$)/g; function twoSpaceNumber(num) { return num.replace(regex, "$& "); } const strings = ['123456789','012345678']; for (const string of strings) { console.log(string, '=>', twoSpaceNumber(string)); }

Answer 3

If you don't mind a non-regex approach:

function twoSpaceNumber(num) { 
    var res = '';
    num += '';
    for(var i = 0; i < num.length; i+=2)
    {    
        res += num.substr(i,2) + ' ';
    }
    return res.trim();
}