我想做一个表单。它的工作方式是用户从10个多个选择复选框中选择最多3个选项。然后他们点击确认位置按钮。最后，他们点击发送电子邮件链接。基本上，当他们单击确认位置按钮时，它会根据他们在多个复选框中的选择(最多3个)更改发送电子邮件链接中的mailto链接。然而，我无法想象的是如何设置多个选择复选框(最大限制为3，最小限制为1)，然后在mailto链接中添加单个/多个电子邮件值。我已经为下拉列表(只有一个选择，因此只有一个电子邮件)做到了这一点，但我不能弄清楚上面的内容。请帮助!
<form>Select your place:
<select id="mySelect">
<option value="email@domain.com">Location 1</option>
<option value="email2@domain.com">Location 2</option>
<option value="email3@domain.com">Location 3</option>
<option value="email4@domain.com">Location 4</option>
</select>
</form>
<button type="button" onclick="displayResult()">Confirm Location</button>
<a id="myEmailList" href="mailto:">Send email</a>
<script type="text/javascript">
function displayResult() {
var x = document.getElementById("mySelect");
t = x.value
document.getElementById("myEmailList").href = "mailto:"t;
}
</script>
JS
function displayResult() {
var se = document.getElementById("myEmailList"),
send = document.getElementById("send"),
x = document.getElementById("mySelect"),
l = [],
// get all checkboxes inside our fieldset that are checked
list = x.querySelectorAll(":checked");
// loop the list and push the email stored in value to our array list
for (i = 0; i < list.length; i++) {
l.push(list[i].value);
}
// use array.join(",") to create a nice email list deliminated by commas
send.href = "mailto:" + l.join(", ");
se.innerHTML = l.join(", ");
}