最简洁 答案~
hi我会努力的
2020-04-26 16:19
<!DOCTYPE html>
<html>
<head>
<title> 事件</title>
<script type="text/javascript">
function count(){
var num1 = document.getElementById("txt1").value;
var num2 = document.getElementById("txt2").value;
var num3 = document.getElementById("select").value;
var sum = 0;
switch(num3){
case '+':
sum = parseInt(num1) + parseInt(num2);
break;
case '-':
sum = parseInt(num1) - parseInt(num2);
break;
case '*':
sum = parseInt(num1) * parseInt(num2);
break;
case '/':
sum = parseInt(num1) / parseInt(num2);
break;
}
document.getElementById("fruit").value=sum;
}
</script>
</head>
<body>
<input type='text' id='txt1' />
<select id='select'>
<option value='+'>+</option>
<option value="-">-</option>
<option value="*">*</option>
<option value="/">/</option>
</select>
<input type='text' id='txt2' />
<input type='button' value=' = ' onclick="count()"/>
<input type='text' id='fruit' />
</body>
</html>
2回答
-
- 慕用2704297
- 2020-05-24 16:38:35
为啥parseInt不应用在num1获取的时候呢，var num1 = parseInt(document.getElementById("txt1").value);
-
- 慕盖茨8203141
- 2020-05-24 14:51:36
<!DOCTYPE html><html> <head> <title> 事件</title> <script type="text/javascript"> function count(){ var i1=document.getElementById('txt1').value; var i2=document.getElementById('txt2').value; var i3; switch(document.getElementById('select').value){ case '+': i3=parseInt(i1)+parseInt(i2); break; case '-': i3=parseInt(i1)-parseInt(i2); break; case '*': i3=parseInt(i1)*parseInt(i2); break; case '/': i3=parseInt(i1)/parseInt(i2); break; } document.getElementById('fruit').value=i3; //获取第一个输入框的值 //获取第二个输入框的值 //获取选择框的值 //获取通过下拉框来选择的值来改变加减乘除的运算法则 //设置结果输入框的值 } </script> </head> <body> <input type='text' id='txt1' /> <select id='select'> <option value='+'>+</option> <option value="-">-</option> <option value="*">*</option> <option value="/">/</option> </select> <input type='text' id='txt2' /> <input type='button' value=' = ' onclick="count()" /> <!--通过 = 按钮来调用创建的函数，得到结果--> <input type='text' id='fruit' /> </body></html>
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