<!DOCTYPE html><html> <head> <title> 事件</title> <script type="text/javascript"> function count(){ var a; var txt1=document.getElementById("txt1").value; var txt2=document.getElementById("txt2").value; var txt3=document.getElementById("txt3").value; switch(txt3){ case "+" a=parseInt(txt1)+parseInt(txt2); break case "-" a=parseInt(txt1)-parseInt(txt2); break case "*" a=parseInt(txt1)*parseInt(txt2); break case "/" a=parseInt(txt1)/parseInt(txt2); break } document.getElementById('fruit').value=a; } </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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慕斯卡8036547
TA贡献10条经验 获得超5个赞
很多地方都有问题，各种毛病，自己对比下吧
<!DOCTYPE html>
<html>
<head>
<title> 事件</title>
<script type="text/javascript">
function count(){
var a;
var txt1=document.getElementById("txt1").value;
var txt2=document.getElementById("txt2").value;
var txt3=document.getElementById("select").value;
switch(txt3){
case "+":
a=parseInt(txt1)+parseInt(txt2)
break
case "-":
a=parseInt(txt1)-parseInt(txt2)
break
case "*":
a=parseInt(txt1)*parseInt(txt2)
break
case "/":
a=parseInt(txt1)/parseInt(txt2)
break
}
document.getElementById('fruit').value=a;
}
</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>
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