问题描述
- JavaScript onchange运行一次失效
-
载入时运行了一次，之后失效了，代码如下add.jsp
<%@page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <!DOCTYPE html> <html> <head> <meta charset="utf-8"> <link rel="shortcut icon" type="image/x-icon" href="../favicon.ico" /> <title>添加</title> <link href="/IMS/css/css.css" rel="stylesheet" type="text/css"> <script src="/IMS/lib/MakeRequest.js"></script> <script> window.onload = initForm; function initForm() { makeRequest(document.getElementById("aname")); } </script> </head> <body> <form action="Department111" method="post" name="add" id="add"> <input type="hidden" name="action" value="add"> <table> <tr> <td width="120" align="right">名称：</td> <td width="180" align="left"><input name="aname" type="text" id="aname" autofocus="autofocus" date="Department?action=s&name=" class="reqd"></td> </tr> <tr> <td align="right">权限：</td> <td align="left"><input name="level" id="level" class="reqd"></td> </tr> <tr> <td align="right"> <a href="index.jsp">返回</a> </td> <td align="left"><input name="add" type="submit" id="add" value="添加"></td> </tr> </table> </form> </body> </html>MakeRequest.js
function makeRequest(obj) { obj.addEventListener("onchange", makeR(obj), false) function makeR(obj) { console.log(obj); var url = obj.getAttribute("date") + obj.value; console.log(obj.value); console.log(url); if (window.XMLHttpRequest) { xhr = new XMLHttpRequest(); } else { if (window.ActiveXObject) { try { xhr = new ActiveXObject("Microsoft.XMLHTTP"); } catch (e) { console.log(e); } } } if (xhr) { xhr.addEventListener("readystatechange", showContents, false); xhr.open("GET", url, true); xhr.send(null); } else { msg.innerHTML = "Sorry, but I couldn't create an XMLHttpRequest"; } function showContents() { if (xhr.readyState == 4) { if (xhr.status == 200) { var outMsg = xhr.responseXML.getElementsByTagName("s")[0].childNodes[0].nodeValue; if (outMsg == "yes") { alert("已存在"); } } else { var outMsg = "There was a problem with the request " + xhr.status; alert(outMsg); } } } } }
解决方案
obj.addEventListener("onchange", makeR(obj), false)
==>
obj.addEventListener("change", function(){makeR(obj)}, false)
解决方案二：
将 obj.addEventListener("onchange", makeR(obj), false)改为
obj.addEventListener("onchange",function(){makeR(obj);}, false)
解决方案三：
最终版本
function makeRequest(obj) {
obj.addEventListener("blur", function() {
doit(obj)
}, false);
function doit(obj) {
if (obj.value != null) {
var url = obj.getAttribute("date") + obj.value;
var xhr;
if (window.XMLHttpRequest) {
xhr = new XMLHttpRequest();
} else {
if (window.ActiveXObject) {
try {
xhr = new ActiveXObject("Microsoft.XMLHTTP");
} catch (e) {
console.log(e);
}
}
}
if (xhr) {
xhr.addEventListener("readystatechange", showContents, false);
xhr.open("POST", url, true);
xhr.send(null);
} else {
msg.innerHTML = "Sorry, but I couldn't create an XMLHttpRequest";
}
}
function showContents() {
if (xhr.readyState == 4) {
if (xhr.status == 200) {
var outMsg = xhr.responseXML.getElementsByTagName("s")[0].childNodes[0].nodeValue;
if (outMsg == "1") {
alert("【" + obj.value + "】已存在");
obj.focus();
obj.select();
}
} else {
var outMsg = "There was a problem with the request "
+ xhr.status;
alert(outMsg);
}
}
}
}
}
时间： 2024-09-17 04:03:49