Javascript Throttle & Debounce

Throttle

無視一定時間內所有的調用，適合在發生頻度比較高的，處理比較重的時候使用。

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

一定間隔內沒有調用時，才開始執行被呼叫者法。

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);