按了 = 按鈕 沒(méi)反應(yīng)？？求大神解疑。。
? <script type="text/javascript">
?? function count(){
??? var=a,b,c,result;
??? a=document.getElementById('txt1').value;
??? b=document.getElementById('txt2').value;
??? c=document.getElementById('select').value;
??? switch(c):
??? {
??????? case "+":result=parseInt(a)+parseInt(b);break;
??????? case "-":result=parseInt(a)-parseInt(b);break;
??????? case "*":result=parseInt(a)*parseInt(b);break;
??????? case "/":result=parseInt(a)/parseInt(b);break;
??? }
??? 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>
2017-08-29
三個(gè)問(wèn)題，聲明多變量時(shí)
var? ?result，
??????? a=document.getElementById('txt1').value;
??????? b=document.getElementById('txt2').value;
??????? c=document.getElementById('select').value;
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switch 語(yǔ)句中沒(méi)有冒號(hào)
switch() {
}
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onclick=count() 不要加引號(hào)
2017-09-20
switch的每一個(gè)case后面有break；配套