最近学习javascript的时候看的Javascript DOM编程艺术,中间作者提到了addLoadEvent()
函数,用来在页面加载完成后调用函数。
但发现有个函数会调用两次,求解答。
html文件代码:
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8" />
<title>Hello</title>
</head>
<body>
<script src="../script/addLoadEvent.js"></script>
<script src="../script/new_file.js"></script>
<script src="../script/new_file1.js"></script>
</body>
</html>
js代码:
addLoadEvent.js
function addLoadEvent(func) {
var oldonload = window.onload;
if(typeof window.onload != 'function') {
window.onload = func;
} else {
oldonload();
func();
}
}
new_file.js代码:
function fun1() {
alert("fun1");
}
addLoadEvent(fun1);
new_file1.js代码:
function fun2() {
alert("fun2");
}
addLoadEvent(fun2);
运行时,会出现两次fun1 一直不懂,求大神解答