Javascript 如果所选用户名已存在，则提醒用户
此代码位于由表单的Javascript 如果所选用户名已存在，则提醒用户,javascript,php,mysql,Javascript,Php,Mysql,此代码位于由表单的onsubmit事件触发的JavaScript函数中 var username = document.register.username.value; var phpUsernameFree = <?php $username = "<script>document.write(username)</script>"; $resultTempUsers = mysql_query("SELECT * FROM tempUsers
onsubmitvar username = document.register.username.value;
var phpUsernameFree = <?php
$username = "<script>document.write(username)</script>";
$resultTempUsers = mysql_query("SELECT * FROM tempUsers WHERE username = '$username' ") or die(mysql_error());
if( mysql_num_rows($resultTempUsers) == 0 ){
echo 1;
};
?> ;
if( phpUsernameFree == 0){
toggleNew('usernameAlreadyExists', 1);
usernameCounter = 1;
}
<?php
*include connection to database here*
$data = $_POST["data"];
$type = $_POST["type"];
$resultUsers = mysql_query("SELECT * FROM users WHERE username = '$data' ") or die(mysql_error());
if( mysql_num_rows($resultUsers) == 1 ){
echo 1;
}
?>
$("#inputId").keyUp(function(){
//This event, raised when the textbox value changed
//inside this event, you can call ajax function and check user existance and if result is false you can disable the submit button
});
<script>
function Login(str) {
if (str.length == 0) {
document.getElementById("txtHint").innerHTML = "";
return;
} else {
var xmlhttp = new XMLHttpRequest();
xmlhttp.onreadystatechange = function() {
if (xmlhttp.readyState == 4 && xmlhttp.status == 200) {
document.getElementById("Msg").innerHTML = xmlhttp.responseText;
}
}
xmlhttp.open("GET", "Login.php?q=" + str, true);
xmlhttp.send();
}
}
</script>
最好的方法是使用ajax。你应该这样做：
<?php
*include connection to database here*
$data = $_POST["data"];
$type = $_POST["type"];
$resultUsers = mysql_query("SELECT * FROM users WHERE username = '$data' ") or die(mysql_error());
if( mysql_num_rows($resultUsers) == 1 ){
echo 1;
}
?>
$("#inputId").keyUp(function(){
//This event, raised when the textbox value changed
//inside this event, you can call ajax function and check user existance and if result is false you can disable the submit button
});
<script>
function Login(str) {
if (str.length == 0) {
document.getElementById("txtHint").innerHTML = "";
return;
} else {
var xmlhttp = new XMLHttpRequest();
xmlhttp.onreadystatechange = function() {
if (xmlhttp.readyState == 4 && xmlhttp.status == 200) {
document.getElementById("Msg").innerHTML = xmlhttp.responseText;
}
}
xmlhttp.open("GET", "Login.php?q=" + str, true);
xmlhttp.send();
}
}
</script>
如果您不想使用Jquery，则需要AJAX来实现这一点。
大概是这样的：
<?php
*include connection to database here*
$data = $_POST["data"];
$type = $_POST["type"];
$resultUsers = mysql_query("SELECT * FROM users WHERE username = '$data' ") or die(mysql_error());
if( mysql_num_rows($resultUsers) == 1 ){
echo 1;
}
?>
$("#inputId").keyUp(function(){
//This event, raised when the textbox value changed
//inside this event, you can call ajax function and check user existance and if result is false you can disable the submit button
});
<script>
function Login(str) {
if (str.length == 0) {
document.getElementById("txtHint").innerHTML = "";
return;
} else {
var xmlhttp = new XMLHttpRequest();
xmlhttp.onreadystatechange = function() {
if (xmlhttp.readyState == 4 && xmlhttp.status == 200) {
document.getElementById("Msg").innerHTML = xmlhttp.responseText;
}
}
xmlhttp.open("GET", "Login.php?q=" + str, true);
xmlhttp.send();
}
}
</script>
类似的，不起作用，但这是一个想法。使用普通按钮代替提交按钮，根据响应值在ajax响应后提交表单
<!DOCTYPE html>
<html>
<head>
<title>Test</title>
<script>
function checkUserExistence(){
var username = document.register.username.value;
var xmlhttp;
if (window.XMLHttpRequest) { xmlhttp = new XMLHttpRequest();} else { xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");}
xmlhttp.onreadystatechange = function() {
if (xmlhttp.readyState == 4 ) {
if(xmlhttp.status == 200){
phpUsernameFree = xmlhttp.responseText;
if( phpUsernameFree == 0){
alert("username Already Exists");
} else {
alert("username available.");
register.submit();
}
} else if(xmlhttp.status == 400) {
alert("There was an error 400");
} else {
alert("something else other than 200 was returned");
}
}
}
xmlhttp.open("GET", "service.php?username=" + username, true);
xmlhttp.send();
}
</script>
</head>
<body>
<form id="register" name="register" method="post">
<input type="text" name="username" id="username" value="check" />
<input type="button" id="save" name="save" value="Save" onclick="checkUserExistence();" />
</form>
</body>
</html>
<!-- service.php -->
<?php
$username = $_REQUEST["username"];
$resultTempUsers = mysql_query("SELECT * FROM tempUsers WHERE username = '$username' ") or die(mysql_error());
if( mysql_num_rows($resultTempUsers) == 0 ){
echo 1;
};
?>
测验
函数checkUserExistence（）{
var username=document.register.username.value；
var-xmlhttp；
if（window.XMLHttpRequest）{xmlhttp=new-XMLHttpRequest（）；}else{xmlhttp=new-ActiveXObject（“Microsoft.xmlhttp”）；}
xmlhttp.onreadystatechange=函数（）{
if（xmlhttp.readyState==4）{
if（xmlhttp.status==200）{
phpUsernameFree=xmlhttp.responseText；
if（phpUsernameFree==0）{
警报（“用户名已存在”）；
}否则{
警报（“用户名可用”）；
注册。提交（）；
}
}else if（xmlhttp.status==400）{
警报（“出现错误400”）；
}否则{
警报（“返回了200以外的内容”）；
}
}
}
open（“GET”，“service.php？username=“+username，true”）；
xmlhttp.send（）；
}
看看ajax；如果您试图让浏览器执行此逻辑，则不会发生。您需要一些与服务器接口的东西。如果您使用jqueryajax函数，它会更简单……您可以参考这个示例了解代码