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);