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點擊=沒反應，不知道問題出在哪里，求幫忙

<!DOCTYPE html>
<html>
?<head>
? <title> 事件</title> ?
? <script type="text/javascript">
?? function count()
?? {
??? var d = "";
??? var a= document.getElementById("txt1").value;
??? var b= document.getElementById("txt2").value;
??? var c= document.getElementById("select").value;
??? switch(c)
??????? {
??????????? case "+":
??????????? d = parseInt(a)+parseInt(b);
??????????? break;
??????????? case "-":
??????????? d = a-b;
??????????? break;
??????????? case "*":
??????????? d = a*b;
??????????? break;
??????????? default:
??????????? d = a/b;
??????? }
??? document.getElementById({"fruit").value = d ;
?? }
? </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>

1小時先生

2016-08-31

源自：JavaScript進階篇 6-11

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2 回答

imalwayshere
2016-08-31

function?count(){
????var?num1=parseFloat(document.getElementById("txt1").value);
????var?num2=parseFloat(document.getElementById("txt2").value);
????var?result=document.getElementById("fruit");
????var?op=document.getElementById("select").value;
????switch(op){
????????case'+':result.value=num1+num2;break;
????????case'-':result.value=num1-num2;break;
????????case'*':result.value=num1*num2;break;
????????case'/':result.value=num1/num2;break;
}

這樣是不是簡潔點。