Javascript 不获取输入数字的值

Question

这个问题已经有答案了:

How to make a document.getElementById value into an integer variable, not a string? (6 个回答)

Using <form> and <input> elements as an input for JavaScript code. Is this the best way to do this? (2 个回答)

已关闭 8 年前。

我正在用javascript编写一个程序，用户必须输入数字，计算机将根据这些数字进行计算。然而，当我编写 Javascript 来添加两个输入的数字时，它只是将它们放在一起而不是相加。例如，当它必须添加 4 + 4 时，输出是 44，而不是 8。

<form>
    <p> Give side 1</p>
 <br>
<input type="number"  id="side1">  
<br><br>
<p> Give side 2</p>
 <br>
<input type="number"  id="side2">  
 <br><br>
  <p> Give side 3</p>
  <br>
 <input type="number"  id="side3">  
<br><br>

<button type="button" onClick="my()"> Calculate</button>
<p id="sum"></p>


</form>


</center>
<script type="text/javascript">
function my() {
var a= document.getElementById("side1").value;
var b= document.getElementById("side2").value;
var c= document.getElementById("side3").value;
var d= a + b + c;
    document.getElementById("sum").innerHTML="The are o the triangle is " + "" + d;
}




</script>

Answer 1

这正在工作。您只需使用 parseInt:

function my() {
    var a = parseInt(document.getElementById("side1").value, 10);
    var b = parseInt(document.getElementById("side2").value, 10);
    var c = parseInt(document.getElementById("side3").value, 10);
    var d = a + b + c;
    document.getElementById("sum").innerHTML = "The are o the triangle is " + "" + d;
}

fiddle

引用:

parseInt()