JavaScript: setTimeout不会暂停循环
JavaScript: setTimeout不会暂停循环
提问于 2016-08-02 00:10:57
我需要在我的循环中做一些延迟，每次在一定数量的数据(在我的循环中经过几次循环/迭代之后)被发送到服务器之后。
从服务器发送数据和接收响应工作得很好，但循环中请求的延迟仍然不起作用。
非常感谢你的帮助。
编辑:代码已更改，请检查第三个答案(我的)。
<!DOCTYPE html>
<html>
<body>
<h2>AJAX</h2>
<button type="button" onclick="loadDoc()">Request data</button>
<p id="demo"></p>
<script>
function loadDoc() {
var xhttp = [];
var code = [
"WOICEL0Q9P",
"ZJTS4GYJEJ",
"HJPMQOCX31",
"MP26N0BH01",
"7TJNYZIRJR",
"Z5MIDDG4N2",
"BX6MKYK0O7",
"KVFVH1ESQX",
"40ADY3ZBE5",
"V4NT360JR5",
"FDI8AFL680",
"ZH89N59XQR",
"M6OS2OX38H",
"D8O76YDLM0",
"86GBMJLIXY",
"1QRFVU26VK",
"HFUI9QV6DY",
"VN83OGR825",
"DDMPCBX2MF",
"2M3QFPI234"
];
var i = code.length;
var j = code.length;
var k = 5000;
var p = 0;
while (i--) {
var process = (function(i) {
if (p == 5) {
p = 0;
function func(i) {
xhttp[i] = new XMLHttpRequest();
xhttp[i].onreadystatechange = function() {
if (xhttp[i].readyState == 4 && xhttp[i].status == 200) {
if (i == j) {
document.getElementById("demo").innerHTML = code[i] + ": " + xhttp[i].responseText;
}
else {
document.getElementById("demo").innerHTML += "<br><br>" + code[i] + ": " + xhttp[i].responseText;
}
}
};
xhttp[i].open("POST", "https://www.example.com/services/postdata.svc", true);
xhttp[i].setRequestHeader("Host", "www.example.com");
xhttp[i].setRequestHeader("Accept", "application/json, text/javascript");
xhttp[i].setRequestHeader("Accept-Language", "cs,en-US;q=0.7,en;q=0.3");
xhttp[i].setRequestHeader("Accept-Encoding", "gzip, deflate, br");
xhttp[i].setRequestHeader("Content-Type", "application/json; charset=utf-8");
xhttp[i].setRequestHeader("Cache-Control", "no-cache");
xhttp[i].setRequestHeader("X-Requested-With", "XMLHttpRequest");
xhttp[i].setRequestHeader("Referer", "https://www.example.com/postdata-test.htm");
xhttp[i].setRequestHeader("Content-Length", "37");
xhttp[i].setRequestHeader("Connection", "keep-alive");
xhttp[i].send('{"code":"'+code[i]+'","confirm":false}');
//console.log('hello - Test if delay is here');
p++;
}
setTimeout(func(i), k);
k += 5000;
}
else {
xhttp[i] = new XMLHttpRequest();
xhttp[i].onreadystatechange = function() {
if (xhttp[i].readyState == 4 && xhttp[i].status == 200) {
if (i == j) {
document.getElementById("demo").innerHTML = code[i] + ": " + xhttp[i].responseText;
}
else {
document.getElementById("demo").innerHTML += "<br><br>" + code[i] + ": " + xhttp[i].responseText;
}
}
};
xhttp[i].open("POST", "https://www.example.com/services/postdata.svc", true);
xhttp[i].setRequestHeader("Host", "www.example.com");
xhttp[i].setRequestHeader("Accept", "application/json, text/javascript");
xhttp[i].setRequestHeader("Accept-Language", "cs,en-US;q=0.7,en;q=0.3");
xhttp[i].setRequestHeader("Accept-Encoding", "gzip, deflate, br");
xhttp[i].setRequestHeader("Content-Type", "application/json; charset=utf-8");
xhttp[i].setRequestHeader("Cache-Control", "no-cache");
xhttp[i].setRequestHeader("X-Requested-With", "XMLHttpRequest");
xhttp[i].setRequestHeader("Referer", "https://www.example.com/postdata-test.htm");
xhttp[i].setRequestHeader("Content-Length", "37");
xhttp[i].setRequestHeader("Connection", "keep-alive");
xhttp[i].send('{"code":"'+code[i]+'","confirm":false}');
p++;
}
})(i);
}
}
</script>
</body>
</html>Stack Overflow用户
发布于 2016-08-02 00:15:50
您不断地在while中立即产生对process()的多个调用，然后告诉process在回调发生之前等待5秒。
// Run this loop over and over again
while (true) {
// Create a function called process that process data
var process = (function () {
// Do something with data
console.log("Something");
// Wait a few seconds and do it again
setTimeout(process, 5000);
// This () right here says call process right now
}());
}页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/38703456
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