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.