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                        /JavaScript進(jìn)階篇

為什么點(diǎn)=號(hào)不出結(jié)果?。扛魑淮笊?。

<!DOCTYPE html>
<html>
?<head>
? <title> 事件</title>?
? <script type="text/javascript">
?? function count(){
??????? var t1=document.getElementById("txt1").value;
??????
??? //獲取第一個(gè)輸入框的值
??????? var t2=document.getElementById("txt2").value;
?//獲取第二個(gè)輸入框的值
???? var a=document.getElementById("select").value;
???? var result="";
?//獲取選擇框的值
?stwich(a){
????
????? case "+":
????? result=parseFloat(t1)+parseFloat(t2);
????? break;
????? case "-":
????? result=parseFloat(t1)-parseFloat(t2);
????? break;
????? case "*":
????? result=parseFloat(t1)*parseFloat(t2);
????? break;
????? case "/":
????? result=parseFloat(t1)/parseFloat(t2);
????? break;
????????
????
?}
?document.getElementById("fruit").value = result;
?
?//獲取通過(guò)下拉框來(lái)選擇的值來(lái)改變加減乘除的運(yùn)算法則
??? //設(shè)置結(jié)果輸入框的值
???
?? }
? </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()"/> 
?? <input type='text' id='fruit' />??
?</body>
</html>