regex replace words javascript code example

Example 1: js replace characters in a string

var str = "Original string!";
var str = str.replace("Original", "New");

Example 2: how to replace all the string in javascript when the string is javascript variable

function name(str,replaceWhat,replaceTo){
    var re = new RegExp(replaceWhat, 'g');
    return str.replace(re,replaceTo);
}