javascript replace all with variable

function name(str,replaceWhat,replaceTo){
    replaceWhat = replaceWhat.replace(/[-\/\\^$*+?.()|[\]{}]/g, '\\$&');
    var re = new RegExp(replaceWhat, 'g');
    return str.replace(re,replaceTo);
}function name(str,replaceWhat,replaceTo){
    var re = new RegExp(replaceWhat, 'g');
    return str.replace(re,replaceTo);
}/**
*A better method for replacing strings is as follows:
**/
function replaceString(oldString, newString, fullString) {
  return fullS.split(oldS).join(newS)
}
replaceString('World', 'Web', 'Brave New World')//'Brave New Web'
replaceString('World', 'Web', 'World New World')//'Web New Web'