Javascript replace all line breaks in a string with

1. str = str.replace('\n', '<br />');  -> However, this only replace the first ocurrence
2. str = str.replace(/\n/g, '<br />'); -> use regexp to do global match
3. str.replace(new RegExp('\n','g'), '<br />') -> similar to #2, but use constructor to build RegExp
4. str = str.split("\n").join("<br />"); -> split and join, another way to do replace
5. String.prototype.replaceAll = function(needle, replacement) {return this.split(needle).join(replacement||"");}; -> similar to #4, but added to String prototype

Btw, probably we need take care of \r\n case.