求大神指點下。點擊“=”按鈕，沒有反應呢?
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<script type="text/javascript">
function count(){
?? ?var num1=document.getElementById("num1").value ,
symble=document.getElementById("symble"), ? ???? num2=document.getElementById("num2").value ,
?? ??? ?result;
?? ??? ?switch(symble){
?? ??? ??? ?case"+":
?? ??? ??? ?result=parseInt(num1)+parseInt(num2);
?? ??? ??? ?break;
?? ??? ??? ?case"-":
?? ??? ??? ?result=parseInt(num1)-parseInt(num2);
?? ??? ??? ?break;
?? ??? ??? ?case"*":
?? ??? ??? ?result=parseInt(num1)*parseInt(num2);
?? ??? ??? ?break;
?? ??? ??? ?case"/":
?? ??? ??? ?result=parseInt(num1)/parseInt(num2);
?? ??? ??? ?break;
?? ??? ??? ?default:
?? ??? ??? ?result=null;
?? ??? ??? ?}
?? ??? ??? ?document.getElementById("num3") = result;
?? ??? ?}
</script>>
<title>計算器簡單功能實現(xiàn)</title>
</head>
<body>
<input type="text" name="num" id="num1">
<select id="symble">
<option>+</option>
<option>-</option>
<option selected="selected">*</option>
<option>/</option>
</select>
<input type="text" name="num" id="num2">
<input type="button" value="=" onclick = "count()">
<input type="text" name="num" id="num3">
</body>
</html>
2018-07-15
<!DOCTYPE HTML>
<html>
<head>
?<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
?<script type="text/javascript">
? ?function count() {
? ? ?var num1 = document.getElementById("num1").value,
? ? ? ?symble = document.getElementById("symble").value,
? ? ? ?num2 = document.getElementById("num2").value,
? ? ? ?result;
? ? ?switch (symble) {
? ? ? ?case "+":
? ? ? ? ?result = parseInt(num1) + parseInt(num2);
? ? ? ? ?break;
? ? ? ?case "-":
? ? ? ? ?result = parseInt(num1) - parseInt(num2);
? ? ? ? ?break;
? ? ? ?case "*":
? ? ? ? ?result = parseInt(num1) * parseInt(num2);
? ? ? ? ?break;
? ? ? ?case "/":
? ? ? ? ?result = parseInt(num1) / parseInt(num2);
? ? ? ? ?break;
? ? ? ?default:
? ? ? ? ?result = null;
? ? ?}
? ? ?document.getElementById("num3").value = result;
? ?}
?</script>
?<title>計算器簡單功能實現(xiàn)</title>
</head>
<body>
?<input type="text" name="num" id="num1">
?<select id="symble">
? ?<option>+</option>
? ?<option>-</option>
? ?<option selected="selected">*</option>
? ?<option>/</option>
?</select>
?<input type="text" name="num" id="num2">
?<input type="button" value="=" onclick="count()">
?<input type="text" name="num" id="num3">
</body>
</html>
2018-07-15
symble=document.getElementById("symble")是獲取id為symble這個對象，而不是它的值。
應該寫為 ? ? ?symble=document.getElementById("symble").value
同樣的問題：
?document.getElementById("num3").value = result;