<!DOCTYPE?html>
<html>
?<head>
??<title>?事件</title>??
??<script?type="text/javascript">
???function?count(){
????var?result="";
????//獲取第一個輸入框的值
????var?a=document.getElementById("txt1").value;
//獲取第二個輸入框的值
var?b=document.getElementById("txt2").value;
//獲取選擇框的值
var?c=document.getElementById("select").value;
//獲取通過下拉框來選擇的值來改變加減乘除的運算法則
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);
}
????//設(shè)置結(jié)果輸入框的值?
????document.getElementById("fruit").value;
???}
??</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?=?按鈕來調(diào)用創(chuàng)建的函數(shù)，得到結(jié)果-->?
???<input?type='text'?id='fruit'?/>???
?</body>
</html>
2017-09-11
count()的最后應(yīng)該用document.getElementById("fruit").value = result;將結(jié)果寫入最后的文本框