哪里不對(duì)？
<!DOCTYPE html>
<html>
?<head>
? <title> 事件</title> ?
? <script type="text/javascript">
?? function count(){
????? ?
??? //獲取第一個(gè)輸入框的值
??? var a = document.getElementById('text').value;
?? ?//獲取第二個(gè)輸入框的值
??? var b = document.getElementById('text2').value;
?? ?//獲取選擇框的值
??? var c = document.getElementById('select').value;
??? var 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
??? switch(e){
??????????? case "+":
??????????? result=a+b;
??????????? break;
??????????? case "-":
??????????? result=a-b;
??????????? break;
??????????? case "*":
??????????? result=a*b;
??????????? break;
??????????? case "/":
??????????? 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()"/> <!--通過(guò) = 按鈕來(lái)調(diào)用創(chuàng)建的函數(shù)，得到結(jié)果-->
?? <input type='text' id='fruit' />? ?
?</body>
</html>
2015-06-23
獲取第一個(gè)框跟第二個(gè)框的值時(shí),書寫錯(cuò)誤 ?兩個(gè)框的id值分別為:txt1,txt2
switch傳進(jìn)來(lái)的參數(shù)應(yīng)該是c,而不是e
進(jìn)行加法運(yùn)算的時(shí)候,一定要進(jìn)行轉(zhuǎn)換,?正確為result=parseInt(a)+parseInt(b); ?若不進(jìn)行轉(zhuǎn)換,js會(huì)以為你只想要簡(jiǎn)單的字符串相加,所以當(dāng)result=a+b的時(shí)候,答案是錯(cuò)誤的.