Some funny little regexes I conjured up for an edge case project.

gistfile1.txt

String.prototype.replaceAllButLast = function( search, replace ) {
  var tmp = this.slice(0, this.lastIndexOf(search)),
		end = this.slice(this.lastIndexOf(search)),
		regex = new RegExp(search.replace(/[\-\[\]\/\{\}\(\)\*\+\?\.\\\^\$\|]/g, "\\$&"), 'g'); // Escaping chars
	
	return tmp.replace(regex,replace) + end;
}

String.prototype.replaceAllButFirst = function( search, replace ) {
	var tmp = this.slice( this.indexOf(search)),
		start = this.slice( 0, this.indexOf(search)),
		regex = new RegExp(search.replace(/[\-\[\]\/\{\}\(\)\*\+\?\.\\\^\$\|]/g, "\\$&"), 'g'); // Escaping chars
	console.log(start);
	return search + tmp.replace(regex,replace);
}