Javascript Throttle & Debounce

Throttle

无视一定时间内所有的调用，适合在发生频度比较高的，处理比较重的时候使用。

var throttle = function (func, threshold, alt) {

    var last = Date.now();

    threshold = threshold || 100;



    return function () {

        var now = Date.now();



        if (now - last < threshold) {

            if (alt) {

                alt.apply(this, arguments);

            }

            return;

        }



        last = now;

        func.apply(this, arguments);

    };

};

Debounce

一定间隔内没有调用时，才开始执行被调用方法。

var debounce = function (func, threshold, execASAP) {

    var timeout = null;

    threshold = threshold || 100;



    return function () {

        var self = this;

        var args = arguments;

        var delayed = function () {

            if (!execASAP) {

                func.apply(self, args);

            }

            timeout = null;

        };



        if (timeout) {

            clearTimeout(timeout);

        } else if (execASAP) {

            func.apply(self, args);

        }



        timeout = setTimeout(delayed, threshold);

    };

};

Test

var test = function (wrapper, threshold) {

    var log = function () {

        console.log(Date.now() - start);

    };

    var wrapperedFunc = wrapper(log, threshold);

    var start = Date.now();

    var arr = [];



    for (var i = 0; i < 10; i++) {

        arr.push(wrapperedFunc);

    }



    while(i > 0) {

        var random = Math.random() * 1000;

        console.log('index: ' + i);

        console.log('random: ' + random);

        setTimeout(arr[--i], random);

    }

};



test(debounce, 1000);

test(throttle, 1000);