<!DOCTYPE?html><html>?<head>??<title>?事件</title>????<script?type="text/javascript">???function?count(){???????????//獲取第一個(gè)輸入框的值????var?a=?document.getElementById("txt1"）.value;????var?num1=parseInt(a); //獲取第二個(gè)輸入框的值 var?b=?document.getElementById("txt2"）.value; var?num2=parseInt(b); //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(yùn)算法則 var?d; switch(c){ ???case?"+"?: ???????d=num1+num2; ???????break; ???case?"-": ???????d=num1-num2; ???????break; ???case?"*": ???????d=num1*num2; ???????break; ???case?"/": ???????d=num1/num2; ???????break; } //設(shè)置結(jié)果輸入框的值?? document.getElementById("fruit").value?=?d;???}??</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>
2022-05-07
a,b,c獲取值的時(shí)候小括號不對，要用英文的