為什么不顯示結(jié)果
<!DOCTYPE?html>
<html>
?<head>
??<title>?事件</title>??
??<script?type="text/javascript">
???function?count(){
????var?num1=parseInt(document.getElementById('txt1'));
????var?num2=parseInt(document.getElementById('txt2'));
????var?opt=document.getElementById('select');
????var?result="";
????switch(opt){
??????case?"+":
????????result=num1+num2;
????????break;
??????case?"-":
????????result=num1-num2;
????????break;
??????case?"*":
????????result=num1*num2;
????????break;
??????case?"/":
????????result=num1/num2;
????}
????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>點(diǎn)了按鈕后面結(jié)果沒(méi)反應(yīng)
2017-02-25
var?num1=parseInt(document.getElementById('txt1')); ------------------你的
請(qǐng)改成----------var?num1=parseInt(document.getElementById('txt1').value);
num2同理 ? opt也加個(gè).value ? ?
document.getElementById('txt1')只是拿到這個(gè)標(biāo)簽 ? .value才能獲取和改變他的文本框里的值
額 看你最后好像知道 ?可能前面忘了吧