我正在尝试编写一个代码,如果用户名/邮件已经注册,将检入php文件。以下代码不起作用,因为在check_fields()中,当两个文件都触发check_field()时,立即发送返回,而不等待异步查询完成。我不想使用JQuery,所以我考虑做以下事情:
<span id="username_err"></>
和<span id="mail_err"></>
的.textContent,以查看php是否注意到错误。如果它不是空白(输入中存在问题),则函数将false返回到初始函数。这就是我想尝试的,这可以吗?有没有办法在没有承诺的情况下做到这一点?
[原始代码]
<html>
<body>
<form style="text-align:center" action="mama.php" method="post" onsubmit="return check()">
<div class="username">
<span id="label_username">Username :</span>
<input type="text" id="username" name="username">
<p id="username_err"></p>
</div><br />
<div class="mail">
<span id="label_mail">Mail :</span>
<input type="text" id="mail" name="mail"></input>
<p id="mail_err"></p>
</div><br />
<input type="submit" id="envoyer" value="Envoyer" />
</form>
</body>
<script>
function check() {
return check_fields(['username', 'mail']);
}
function check_fields(items) {
var check = true;
for (i = 0; i < items.length; i++) {
check_field(items[i]);
};
for (i = 0; i < items.length; i++) {
var value = document.getElementById(items[i] + '_err').textContent;
if (value != '') {
check = false
}
};
return check
}
function check_field(id) {
var value = document.getElementById(id).value;
ajax_php(id, value, 'check_field.php', function(returned_value) {
document.getElementById(id + '_err').innerHTML = returned_value;
});
}
function ajax_php(id, value, file, fn) {
var xmlhttp = new XMLHttpRequest();
xmlhttp.onreadystatechange = function() {
if (xmlhttp.readyState == 4 && xmlhttp.status == 200) {
fn(xmlhttp.responseText);
}
};
xmlhttp.open('GET', file + '?' + id + '=' + value, true);
xmlhttp.send();
}
</script>
</html>
[可能的解决方案]
<html>
<body>
<form style="text-align:center" action="mama.php" method="post" onsubmit="check(this)">
<div class="username">
<span id="label_username">Username :</span>
<input type="text" id="username" name="username">
<p id="username_err"></p>
</div><br />
<div class="mail">
<span id="label_mail">Mail :</span>
<input type="text" id="mail" name="mail"></input>
<p id="mail_err"></p>
</div><br />
<input type="submit" id="envoyer" value="Envoyer" />
</form>
</body>
<script>
function check_fields(form, items) {
var success = true;
function check_field(i) {
var id = items[i];
var value = document.getElementById(id).value;
ajax_php(id, value, 'check_field.php', function(returned_value) {
document.getElmentById(id + '_err').textContent = returned_value;
if (returned_value != '') {
success = false;
}
if (++i < items.length) {
check_field(i); // Check the next field
} else if (success) { // reached the last field with no errors
form.submit();
}
});
}
check_field(0);
}
function check(form) {
check_fields(form, ['username', 'mail']);
return false; // prevent form submission
}
function ajax_php(id, value, file, fn) {
var xmlhttp = new XMLHttpRequest();
xmlhttp.onreadystatechange = function() {
if (xmlhttp.readyState == 4 && xmlhttp.status == 200) {
fn(xmlhttp.responseText);
};
};
xmlhttp.open('GET', file + '?' + id + '=' + value, true);
xmlhttp.send();
};
</script>
</html>
答案 0 :(得分:0)
为每个字段链接AJAX调用。字段i
的回调提交AJAX调用以检查字段i+1
,依此类推。如果一切成功,最后一个回调将提交表单。
function check_fields(form, items) {
var success = true;
function check_field(i) {
var id = items[i];
var value = document.getElementById(id).value;
ajax_php(id, value, 'check_field.php', function(returned_value) {
document.getElementById(id + '_err').textContent = returned_value;
if (returned_value != '') {
success = false;
}
if (++i < items.length) {
check_field(i); // Check the next field
} else if (success) { // reached the last field with no errors
form.submit();
}
});
}
check_field(0);
}
function check(form) {
check_fields(form, ['username', 'mail']);
return false; // prevent form submission
}
表格应包含:
onsubmit="return check(this)"