<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
</head>
<body>
</body>
<script>
var listeners = [];
var doc = document;
var MutationObserver = MutationObserver || WebKitMutationObserver;
var observer;
function observerEleReady(selector, fn) {
// 储存选择器和回调函数
listeners.push({
selector: selector,
fn: fn
});
if (!observer) {
// 监听document变化
observer = new MutationObserver(check);
observer.observe(doc.documentElement, {
childList: true,
subtree: true
});
}
// 检查该节点是否已经在DOM中
check();
}
function check() {
// 检查是否匹配已储存的节点
for (var i = 0; i < listeners.length; i++) {
var listener = listeners[i];
// 检查指定节点是否有匹配
var elements = document.querySelectorAll(listener.selector);
for (var j = 0; j < elements.length; j++) {
var element = elements[j];
// 确保回调函数只会对该元素调用一次
if (!element.ready) {
element.ready = true;
// 对该节点调用回调函数
listener.fn.call(element, element);
}
}
}
}
setTimeout(function(){
document.body.innerHTML = "<h1>aserfdsthhhh</h1>"
}, 1000);
observerEleReady("h1", function(){
console.log("h1加载完成")
})
</script>
</html>
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