=運行怎么沒反應(yīng)
<!DOCTYPE?html>
<html>
?<head>
??<title>?事件</title>??
??<script?type="text/javascript">
???function?count(){
????var?a?=?document.getElementById('text1').value;
????var?b?=?document.getElementById('select').value;
????var?c?=?document.getElementById('txt2').value;
????var?result?;
??switch(b){
????case?"+":
??????result?=?parseFloat(a)?+?parseFloat(c);
??????break;
????case?"-":
??????result?=?parseFloat(a)?-?parseFloat(c);
??????break;
????case?"*":
??????result?=?parseFloat(a)?*?parseFloat(c);
??????break;
????default:
??????result?=?parseFloat(a)?/?parseFloat(c);
??????
??}
??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><br>
???<input?type='text'?id='txt2'?/>?
???<input?type='button'?value='?=?'?onclick="count()"?/>?<br><!--通過?=?按鈕來調(diào)用創(chuàng)建的函數(shù)，得到結(jié)果-->?
???<input?type='text'?id='fruit'?disabled/>???
?</body>
</html>
2020-07-01
var?a?=?document.getElementById('text1').value中ID名寫錯了，應(yīng)為var?a?=?document.getElementById('txt1').value;