問題描述

您好，我目前正在發(fā)出 xmhhttp 請求，但該網(wǎng)站需要一些時(shí)間來加載，所以我只得到 ReadyState = 3 和狀態(tài) = 200.所以我需要等到 readystate = 4 的東西，但我想限制如果readystate = 4，它每秒只檢查一次，否則什么也不做.

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.

這樣的延遲函數(shù)長什么樣子?

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);
  }

推薦答案

我們可以寫一個(gè)函數(shù)來檢查你的 xmlhttp-object 的狀態(tài):

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);
  }
};

那么你可以這樣使用它:

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
});

不過有兩件事:

• 無論 readyState 是什么，checkState 函數(shù)都會(huì)返回，因此請確保您只在回調(diào)中執(zhí)行依賴于它的操作，而不是之后.
• 如果 readyState 和 status 從來沒有得到你想要的值，那么你就不走運(yùn)了(但你可以擴(kuò)展函數(shù)以接受第二個(gè)回調(diào)來處理超時(shí)情況).

這篇關(guān)于需要一個(gè)延遲函數(shù)javascript的文章就介紹到這了，希望我們推薦的答案對大家有所幫助，也希望大家多多支持html5模板網(wǎng)！