当id 为action的select 标签发生改变时，执行handleChange() 方法
select id="action" onchange="handleChange()"
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
</head>
<body>
<div>
<form action="/upload" method="post" enctype="multipart/form-data">
<input type="hidden" style="display: none" placeholder="id" name="announcement_id" value="{{ announcement.id }}" >
<br>
<input type="text" size="60" value="{{ announcement.name }}" disabled>
<br>
<textarea style="width: 431px; height: 343px" disabled> {{ announcement.content }}</textarea>
<br>
<span>变更结束时间：</span><input id="end_time" disabled type="datetime-local" name="end_time" value="now" >
<br>
<select id="action" onchange="handleChange()" name="select" style="width: 392px;">
<option value="over">变更结束</option>
<option value="delay">推迟结束时间</option>
</select>
<button type="submit" value="提交">提交</button>
</form>
</div>
<script>
// 选择select 后触发动作
function handleChange() {
var obj = document.getElementById('action'); // 定位id
var index = obj.selectedIndex; // 选中索引
var value = obj.options[index].value; // 选中值
if (value == "delay" )(
document.getElementById("end_time").value= {{ announcement.end_time }}
)else if (value == "over" )(
document.getElementById("end_time").value=now
)
{#alert(value);#}
}
</script>
</body>
</html>
标签：end,value,js,handleChange,onchange,id,select From： https://www.cnblogs.com/zhangmingda/p/17270332.html