mout/function/throttle.js

Modular Utilities

var now = require('../time/now');

    /**
     */
    function throttle(fn, delay){
        var context, timeout, result, args,
            cur, diff, prev = 0;
        function delayed(){
            prev = now();
            timeout = null;
            result = fn.apply(context, args);
        }
        function throttled(){
            context = this;
            args = arguments;
            cur = now();
            diff = delay - (cur - prev);
            if (diff <= 0) {
                clearTimeout(timeout);
                prev = cur;
                result = fn.apply(context, args);
            } else if (! timeout) {
                timeout = setTimeout(delayed, diff);
            }
            return result;
        }
        return throttled;
    }

    module.exports = throttle;