需要一个延迟函数javascript
您好，我目前正在发出 xmhhttp 请求，但该网站需要一些时间来加载，所以我只得到 ReadyState = 3 和状态 = 200.所以我需要等到 readystate = 4 的东西，但我想限制如果readystate = 4，它每秒只检查一次，否则什么也不做.
Hi im currently making a xmhhttp request, but the site takes some time to load, so I only get the ReadyState = 3 and status = 200. So I need something that waits until the readystate = 4, but I want to limit this function so that it only checks once a second if the readystate = 4, else do nothing.
这样的延迟函数长什么样子?
How can such a delay function look like?
if (xmlhttp.readyState==4 && xmlhttp.status==200)//Add the delay here so that the else doesn't occur
{
var txt=xmlhttp.responseText;
.....
else {
document.write("status: " + xmlhttp.readyState + " " + xmlhttp.status);
}
推荐答案
我们可以写一个函数来检查你的 xmlhttp-object 的状态:
We can write a function for checking the state of your xmlhttp-object:
var checkState = function(xmlhttp, callback) {
if (xmlhttp.readyState == 4 && xmlhttp.status == 200) {
callback(whatever, arguments, that, you, want, to, send);
} else {
// Check back again 1 sec later
setTimeout(checkState, 1000);
}
};
那么你可以这样使用它:
Then you can use it like this:
checkState(xmlhttp, function(whatever, arguments, you, need) {
// the code here will be run when the readyState is 4 and the status is 200
});
不过有两件事:
- 无论 readyState 是什么，checkState 函数都会返回，因此请确保您只在回调中执行依赖于它的操作，而不是之后.
- 如果 readyState 和 status 从来没有得到你想要的值，那么你就不走运了(但你可以扩展函数以接受第二个回调来处理超时情况).
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