<!DOCTYPE html>
<html>
<head>
<title> 事件</title>
<script type="text/javascript">
function count(){
var text1=document.getElementById('txt1').value;//獲取第一個輸入框的值
var text2=document.getElementById('txt2').value;//獲取第二個輸入框的值
var Add=document.getElementById('select').value;//獲取選擇框的值
var result="";
if (Add === "+") {
result = parseFloat(text1) + parseFloat(text2);
} else if (Add === "-") {
result=parseFloat(text1) - parseFloat(text2);
} else if (Add === "*") {
result=parseFloat(text1) * parseFloat(text2);
} else {
result=parseFloat(text1) / parseFloat(text2);
}//獲取通過下拉框來選擇的值來改變加減乘除的運算法則
//設置結果輸入框的值
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=' = ' οnclick="count()" /> <!--通過 = 按鈕來調用創建的函數，得到結果-->
<input type='text' id='fruit' />
</body>
</html>
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