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手写防抖debounce.html
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手写防抖debounce.html
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<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>debounce TEST</title>
<style>
html {
height: 400%;
}
body {
padding: 16px 32px;
}
pre {
padding: 16px;
line-height: 1.5;
background-color: #f5f5f5;
}
</style>
</head>
<body>
<H3>防抖 debounce</H3>
<pre>
</pre>
<script>
// underscore debounce
function debounce(func, wait, immediate = true) {
var timeout, args, context, timestamp, result;
var later = function () {
var last = Date.now() - timestamp;
if (last < wait && last >= 0) {
timeout = setTimeout(later, wait - last);
} else {
timeout = null;
if (!immediate) {
result = func.apply(context, args);
if (!timeout) context = args = null;
}
}
};
return function () {
context = this;
args = arguments;
timestamp = Date.now();
var callNow = immediate && !timeout;
if (!timeout) timeout = setTimeout(later, wait);
if (callNow) {
result = func.apply(context, args);
context = args = null;
}
return result;
};
}
// 简单版 debounce
function debounce(func, wait) {
var timer = null;
return function () {
var context = this;
var args = arguments;
if (timer !== null) {
clearTimeout(timer);
}
timer = setTimeout(function () {
func.apply(context, args);
}, wait);
};
}
function handle() {
console.log('====== debounce ======', arguments, Date.now());
}
window.addEventListener('scroll', debounce(handle, 1000));
</script>
</body>
</html>