js实现网页简单计算器
<!DOCTYPE html
>
<html lang
="en">
<head
>
<meta charset
="UTF-8">
<meta name
="viewport" content
="width=device-width, initial-scale=1.0">
<meta http
-equiv
="X-UA-Compatible" content
="ie=edge"> <title
>Document
</title
></head
>
<body
>
<input type
="text" id
="txt">
<select name
="" id
="slt">
<option value
="+">+</option
>
<option value
="-">-</option
>
<option value
="*">*</option
>
<option value
="/">/</option
>
</select
>
<input type
="text" id
="txt1">
<button onclick
="show()">=</button
>
<input type
="text" id
="txt2">
<script
>
var oT
=document
.getElementById('txt');
var slt
=document
.getElementById('slt');
var oT1
=document
.getElementById('txt1');
var oT2
=document
.getElementById('txt2');
function show(){
var a
=parseFloat(oT
.value
);
var b
=parseFloat(oT1
.value
);
switch (slt
.value
) {
case "+":
sum
= a
+ b
;
break;
case "-":
sum
= a
- b
;
break;
case "*":
sum
= a
*b
;
break;
case "/":
sum
= a
/ b
;
break;
}
oT2
.value
=sum
;
}
</script
>
</body
>
</html
>
总结： 1.想要达到加减乘除的效果一定要做判断。 2.输入框输出的结果是字符串类型要转换为数字类型，否则会执行字符串拼接。
