我试图禁用＆＃34;名称＆＃34;表单中的文本字段＆＃34;选择＆＃34;在页面加载后选择下拉（当页面加载时它被禁用），即在我选择禁用或启用该字段的其他两个选项之一后，当我回到＆＃34;选择＆＃34;我想要禁用相同的字段。我无法理解为什么我写的javascript会阻止这种情况发生。谢谢！
<script type="text/javascript">
function clickclear(thisfield, defaulttext) {
if (thisfield.value === defaulttext) {
thisfield.value = "";
}
}
function clickrecall(thisfield, defaulttext) {
if (thisfield.value === "") {
thisfield.value = defaulttext;
}
}
function checkPickup() {
if (form.os0.value != "Pickup from Toowong, Brisbane" ) {
form.name.disabled = false; form.name.style.color = '#333';
} else {
form.name.disabled = true; form.name.style.color = '#CCC';
/* Reset form values */
form.name.value = "His/her name";
}
}
</script>
<script type="text/javascript">
function validate(form) {
var errmsg = "Oops, you're required to complete the following fields! \n";
// Various other form validations here
// Validate "Pickup"
if (form.os0.value === "") {
errmsg = errmsg + " - Choose pickup or delivery\n";
}
// Validate "phone"
if (form.phone.value === "" || form.phone.value === "Mobile's best!") {
errmsg = errmsg + " - Your phone number\n";
}
if (form.os0.value != "Pickup from Toowong, Brisbane") {
// Validate "name"
if (form.name.value === "" || form.name.value === "His/her name") {
errmsg = errmsg + " - His/her name\n";
}
}
// Alert if fields are empty and cancel form submit
if (errmsg === "Oops, you're required to complete the following fields! \n") {
form.submit();
} else {
alert(errmsg);
return false;
}
}
</script>
</head>
<body>
<form name="form" action="https://www.paypal.com/cgi-bin/webscr" method="post" onSubmit="return validate(form)">
<p class="row">
<input type="hidden" name="on0" value="Pickup and delivery" />Pickup and delivery<br />
<select name="os0" onchange="checkPickup()">
<option value="" selected >Choose</option>
<option value="Pickup from Toowong, Brisbane">Pickup from Toowong, Brisbane $1.00 AUD</option>
<option value="Brisbane +$23.60">Brisbane +$23.60 =$1.00 AUD</option>
</select>
</p>
<p class="row">Your daytime phone number<br />
<input type="text" name="phone" value="Mobile's best!" onclick="clickclear(this, 'Mobile\'s best!')" onblur="clickrecall(this,'Mobile\'s best!')" />
</p>
<p class="row">Recipient's name<br />
<input style="color: #ccc" class="name" type="text" name="name" value="His/her name" onclick="clickclear(this, 'His/her name')" onblur="clickrecall(this,'His/her name')" disabled />
</p>
<input name="custom" type="hidden" />
<input type="hidden" name="currency_code" value="AUD" />
<input class="button" type="image" src="https://www.paypalobjects.com/en_AU/i/btn/btn_buynowCC_LG.gif" border="0" name="submit" alt="PayPal — The safer, easier way to pay online." />
<img alt="" border="0" src="https://www.paypalobjects.com/en_AU/i/scr/pixel.gif" width="1" height="1"> -->
</form>
</body>
</html>
答案 0 :(得分：0)
这可能是对您所写内容的一个简单误解：
if (form.os0.value != "Pickup from Toowong, Brisbane" ) {
form.name.disabled = false; form.name.style.color = '#333';
} else {
form.name.disabled = true; form.name.style.color = '#CCC';
//
}
用简单的英语翻译成以下内容：
如果值为 NOT
"Pickup from Toowong, Brisbane"，请启用该字段，否则将其禁用。
相当于：
仅在值为
"Pickup from Toowong, Brisbane"时禁用该字段。
我相信您正在寻找的逻辑是：
if (form.os0.value == "Brisbane +$23.60" ) {
form.name.disabled = false; form.name.style.color = '#333';
} else {
form.name.disabled = true; form.name.style.color = '#CCC';
//
}
尽管由于特定案例的参与而使用switch语句对此进行编码可能更为漂亮。
答案 1 :(得分：0)
你打算输入double等于（==）还是三倍等于（===）问题中的拼写错误？基于查看您的代码，我认为您需要一个等于（==）而不是三元组的双精度数。我认为三联可能意味着别的东西。