我有ajax，是与php通信，从twitter帐户接收推文。代码运行正常。唯一的问题是，我希望ajax间歇性地调用php，以便任何更新的tweet自动返回并打印到我的页面，而无需刷新或重新输入twitter id。我需要继续调用getstatus()函数或其他东西吗?或者我是否需要使用我已经开始以某种方式制作的getuupdates () ?以下是我的ajax函数:
// the setInterval function added in the getStatusesX function
function getStatusesX()
{
setInterval(getStatuses(),300000);
}
//Create a cross-browser XMLHttp Request object
function getXMLHttp() {
var xmlhttp;
if (window.ActiveXObject) {
XMLHttp = new ActiveXObject("Microsoft.XMLHTTP");
} else if (window.XMLHttpRequest) {
XMLHttp = new XMLHttpRequest();
} else {
alert("Your browser does not support XMLHTTP!");
}
return XMLHttp;
}
//function that searches for the tweets via php
function getStatuses(){
XMLHttp1 = getXMLHttp();
var userID = document.getElementById("userid").value;
//ajax call to a php file that will extract the tweets
XMLHttp1.open( 'GET', 'twitterTest2.php?userid='+userID, true);
// Process the data when the ajax object changes its state
XMLHttp1.onreadystatechange = function() {
if( XMLHttp1.readyState == 4 ) {
if( XMLHttp1.status ==200 ) { //no problem has been detected
document.getElementById("tweetbox").innerHTML=XMLHttp1.responseText;
}
}
}
XMLHttp1.send(null);
}
//function to intermittently call php to check for updated tweets?
function updateInfo() {
if(XMLHttp1.readyState == 4) {
document.getElementById("tweetbox").innerHTML=XMLHttp1.responseText;
}
}
</script>
然后我将getStatusesX()函数添加到我的表单中，如下所示:
<form>
Input Twitter ID: <input type="text" name="userid" id="userid">
<button type="button" onClick="getStatusesX()";>Get recent tweets</button>
</form>
还是不行。我是否以错误的方式使用setInterval ?
使用setTimeout或setInterval函数
从你的代码中我可以看到，getStatuses有太多的责任，因为除了获取数据之外，它还修改了DOM。
我建议这样写:
function getStatuses(callback) {
//...
XMLHttp1.onreadystatechange = function () {
//...
callback && callback(XMLHttp1); //execute callback if any
};
}
function updateStatuses(callback) {
getStatuses(function (xhr) {
document.getElementById("tweetbox").innerHTML = xhr.responseText;
callback && callback;
});
}
//this function update the statuses and as soon as it's finished, it sets
//a timeout to redo the process in ~10 seconds.
function startUpdatingStatuses() {
updateStatuses(function () {
setTimeout(startUpdatingStatuses, 10000);
});
}
startUpdatingStatuses(); //kick-start everything