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                        /JavaScript進(jìn)階篇

只能算除法，完全不知道問(wèn)題出在哪...

<!DOCTYPE html>
<html>
?<head>
? <title> 事件</title>?
? <script type="text/javascript">
?? function count(){
?????? var a=parseInt(document.getElementById("txt1").value);
?????? var b=parseInt(document.getElementById("txt2").value);
?????? var c=parseInt(document.getElementById("select").value);
?????? var result;
??? //獲取第一個(gè)輸入框的值
?//獲取第二個(gè)輸入框的值
?//獲取選擇框的值
?//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
??? switch(c)
??? {
??????? case '+':
??????????? result=a+b;
??????????? break;
??????? case '-':
??????????? result=a-b;
??????????? break;
??????? case '*':
??????????? break;
??????? default:
??????????? result=a/b;
??????????? break;
??? }
??? //設(shè)置結(jié)果輸入框的值
??? document.getElementById("fruit").value=result;
?? }
? </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>