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看看我的吧，怎么沒有結(jié)果啊

<!DOCTYPE html>
<html>
?<head>
? <title> 事件</title>?
? <script type="text/javascript">
?? function count(){
??? var e1,e2,e3;
??? e1=document.getElementById("txt1").value;
??? e1=parselnt(e1);
??? e2=document.getElementById("txt2").value;
??? e2=parselnt(e2);
??? switch(document.getElementById("select").value){
??????? case="+":
??????????? e3=e1+e2;
??????????? break;
??????? case="-":
??????????? e3=e1+e2;
??????????? break;
??????? case="*":
??????????? e3=e1+e2;
??????????? break;
??????? case="/":
??????? e3=e1+e2;
??????? break;
??????? //default:
??? }
??? document.getElementById("ftuit").value=e3;
?? }
? </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>

慕函數(shù)2531606

2020-03-25

源自：JavaScript進(jìn)階篇 6-11

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3 回答

淺行小生
2020-03-30

1.把每個(gè)case后面的“=”去掉
2.把每個(gè)case的執(zhí)行代碼全"+" 改為 "+" "-" "*" "/"
3.把parseInt提到case "+" 這塊，這個(gè)應(yīng)該是主要原因

<!DOCTYPE html>
<html>
?<head>
? <title>事件</title>?
? <script type="text/javascript">
?? function count(){
??? var e1,e2,e3;
??? e1=document.getElementById("txt1").value;
??? e2=document.getElementById("txt2").value;
??? switch(document.getElementById("select").value){
??????? case "+":
??????????? e3=parseInt(e1)+parseInt(e2);
??????????? break;
??????? case "-":
??????????? e3=e1-e2;
??????????? break;
??????? case "*":
??????????? e3=e1*e2;
??????????? break;
??????? case "/":
??????????? e3=e1/e2;
??????????? break;
??? }
??? document.getElementById("fruit").value=e3;
?? }
? </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>