Created
June 28, 2016 06:26
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节流函数
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<!DOCTYPE html> | |
<html lang="en"> | |
<head> | |
<meta charset="UTF-8"> | |
<title>throttle</title> | |
</head> | |
<body> | |
<div style="height:5000px"> | |
<div id="demo" style="position:fixed;"></div> | |
</div> | |
<script> | |
var COUNT = 0, demo = document.getElementById('demo'); | |
function testFn() {demo.innerHTML += 'testFN 被调用了 ' + ++COUNT + '次<br>';} | |
var throttle = function (fn, delay, atleast) { | |
var timer = null; | |
var previous = null; | |
return function () { | |
var now = +new Date(); | |
if ( !previous ) previous = now; | |
if ( atleast && now - previous > atleast ) { | |
fn(); | |
// 重置上一次开始时间为本次结束时间 | |
previous = now; | |
clearTimeout(timer); | |
} else { | |
clearTimeout(timer); | |
timer = setTimeout(function() { | |
fn(); | |
previous = null; | |
}, delay); | |
} | |
} | |
}; | |
window.onscroll = throttle(testFn, 200); | |
// window.onscroll = throttle(testFn, 500, 1000); | |
</script> | |
</body> | |
</html> |
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