What kind of function is used when hashing in TW

[Jan]

Hi Tiddlydevs,
Thomas Elminger in his hashmacro uses a tw.utils-hash function:

var hash = $tw.utils.hashString(str);

What kind of hash-function does TW use there? How would you enter it in php to reproduce the identical value for the same str serverside.

Thanks for your help!
Best wishes Jan

[Mark S.]

exports.hashString = function(str) {
	return str.split("").reduce(function(a,b) {
		a = ((a << 5) - a) + b.charCodeAt(0);
		return a & a;
	},0);
};