如何在 HTML 中使用带有 select 标签的 if 语句 (JavaScript)？
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How to use the if statement (JavaScript) with the select tag in HTML?
提问by Christian Landgren
I've tried many ways to do this but this isn't right:
我已经尝试了很多方法来做到这一点，但这是不对的：
<html>
<head>
<title>Select</title>
</head>
<body>
<select name="test">
<option value="one">1</option>
<option value="two">2</option>
<option value="three">3</option>
</select>
<script>
if (test=="two") {
document.write("two!");
}
</script>
</body>
</html>
I want to let something appear on the screen if the user chooses "two" but this doesn't work.
如果用户选择“两个”，我想让一些东西出现在屏幕上，但这不起作用。
回答by urfusion
I think this might help you
我想这可能对你有帮助
<select name="test" id="mySelect" onchange="myFunction()">
<option value="one">1</option>
<option value="two">2</option>
<option value="three">3</option>
</select>
<p id="demo"></p>
<script>
function myFunction() {
var x = document.getElementById("mySelect").value;
if(x == "two"){
document.getElementById("demo").innerHTML = "You selected: " + x;
}
}
</script>
Have a look http://jsfiddle.net/snsbbytw/
回答by Stranded Kid
I guess you have to listen to the change event of the select.
我猜你必须听选择的更改事件。
document.getElementsByName("test")[0].addEventListener("change", function(e) {
if (e.target.value === "two") { // not sure if it's e.targe.value, and this might not work in all browsers
document.write("two!");
}
}
回答by Christian Landgren
You are probably looking for the onChange event
您可能正在寻找 onChange 事件
<select name="test" onchange="console.log(this.value)">
Avoid using document.write since it will replace the document output.. And of course, avoid use inline scripting ;)
避免使用 document.write 因为它会替换文档输出.. 当然，避免使用内联脚本 ;)
