Javascript merge function

merge.js

function merge(left, right, sortFieldName){
	var ret = []
	var il = 0
	var ir = 0

	while (il < left.length && ir < right.length) {
		if (left[il][sortFieldName].valueOf() < right[ir][sortFieldName].valueOf()) {
			ret.push(left[il++])
		} else {
			ret.push(right[ir++])
		}
	}
	while(il<left.length) ret.push(left[il++])
	while(ir<right.length) ret.push(right[ir++])
	return ret // ret.concat(left.slice(il)).concat(right.slice(ir));
}