Replace ,(comma) by .(dot) and .(dot) by ,(comma)

Question

I\'ve a string as \"1,23,45,448.00\" and I want to replace all commas by decimal point and all decimal points by comma.

My required output is \"1.23.45.

Answer 1

Use replace with callback function which will replace , by . and . by ,. The returned value from the function will be used to replace the matched value.

var mystring = "1,23,45,448.00";

mystring = mystring.replace(/[,.]/g, function (m) {
    // m is the match found in the string
    // If `,` is matched return `.`, if `.` matched return `,`
    return m === ',' ? '.' : ',';
});

//ES6
mystring = mystring.replace(/[,.]/g, m => (m === ',' ? '.' : ','))

console.log(mystring);
document.write(mystring);

Regex: The regex [,.] will match any one of the comma or decimal point.

String#replace() with the function callback will get the match as parameter(m) which is either , or . and the value that is returned from the function is used to replace the match.

So, when first , from the string is matched

m = ',';

And in the function return m === ',' ? '.' : ',';

is equivalent as

if (m === ',') {
    return '.';
} else {
    return ',';
}

So, basically this is replacing , by . and . by , in the string.

Answer 2

Nothing wrong with Tushar's approach, but here's another idea:

myString
  .replace(/,/g , "__COMMA__") // Replace `,` by some unique string
  .replace(/\./g, ',')         // Replace `.` by `,`
  .replace(/__COMMA__/g, '.'); // Replace the string by `.`