function replaceAll(str, find, replace) {
    var escapedFind=find.replace(/([.*+?^=!:${}()|\[\]\/\\])/g, "\\$1");
    return str.replace(new RegExp(escapedFind, 'g'), replace);
}
//usage example
var sentence="How many shots did Bill take last night? That Bill is so crazy!";
var blameSusan=replaceAll(sentence,"Bill","Susan");