麻烦解释一哈,下面代码:
//obj为div对象,点击时触发f(this)
function f(obj)
{
……
myf(obj)
}
function myf(obj,callback)
{
……
callback&&callback.call(obj)
}
//obj为div对象,点击时触发f(this)
function f(obj)
{
……
myf(obj)
}
function myf(obj,callback)
{
……
callback&&callback.call(obj)
}
callback&&callback.call(obj)
等价于:
if(callback){
callback.call(obj);
}
callback&&callback.call(obj)
这种写法
<html>
<head>
</head>
<body>
<script>
var n = 10000;
console.time('time1');
for(var i = 0; i < n; i++){
document.write && document.write(i+" ");
}
document.write('<br/>');
console.timeEnd('time1');
console.time('time1');
for(var i = 0; i < n; i++){
if(document.write){
document.write(i+" ");
}
}
document.write('<br/>');
console.timeEnd('time1');
</script>
</body>
</html>