如何将用户输入设置为输入值？ [英] how do I set input from user to the value of an input?
问题描述
我正在尝试编写一个简单的程序来计算三角形的面积，但我发现很难从用户那里获得输入。我给输入一个id并将值设置为输入的innerhtml，但它给了我一个默认值1.
I'm trying to write a simple program to calculate the area of a triangle but I'm finding it hard to get input from user. I gave the input an id and set the value to the innerhtml of the input but it's giving me a default value of 1.
<meta name="viewport" content="width=device-width, initial-scale=1" />
<title>Area Of A Triangle</title>
<style type="text/css">
p{
padding:0;
margin:0;
}
</style>
</head>
<body>
<h2>Calculate The Area Of A Triangle</h2>
<p>Enter The Values</p>
<p><input id="firstside" type="text" /></p>
<p><input id="secondside" type="text" /></p>
<p><input id="thirdside" type="text" /></p>
<button id="solve">Submit</button>
<p>Answer Is : <span id="answer"></span></p>
<script type="text/javascript" >
var a; var b; var c; var s; var area;
a= document.getElementById("firstside").value==document.getElementById("firstside").innerHTML;
b= document.getElementById("secondside").value==document.getElementById("secondside").innerHTML;
c= document.getElementById("thirdside").value==document.getElementById("thirdside").innerHTML;
document.getElementById("solve").onclick=function() {
s = (a+b+c);
document.getElementById("answer").innerHTML=s;
}
</script>
</body>
</html>
推荐答案
当您阅读 innerHTML时属性，将元素的所有子节点序列化为HTML，然后将其作为字符串。设置 innerHTML 反过来做同样的事情。
When you read the innerHTML property, you serialize all the child nodes of the element to HTML and then get that as a string. Setting innerHTML does the same thing in reverse.
输入元素没有（也不能）任何子节点（< input> foo< / input> ）都是无效的HTML）。
An input element doesn't (and can't) have any child nodes (<input>foo</input>) is invalid HTML).
其当前值通过其值属性反映出来。
Its current value is reflected through its value property.
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