、、、參考
<!DOCTYPE html>
<html>
?<head>
? <title> 事件</title>??
? <script type="text/javascript">
??
? ?function count(){
var txt1? ?= parseInt( document.getElementById('txt1').value);//獲取第一個輸入框的值
var txt2? ?= parseInt( document.getElementById('txt2').value);//獲取第二個輸入框的值
var select = document.getElementById('select').value;//獲取選擇框的值
var result = '';
switch (select)
{
case '+':
result = txt1 + txt2;
break;
case '-':
result = txt1 - txt2;
break;
case '*':
result = txt1 * txt2;
break;
case '/':
result = txt1 / txt2;
break;??
}
? ? ? ? ?document.getElementById('fruit').value = result;//設置結果輸入框的值?
? ?}
??
? </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 = 按鈕來調用創建的函數，得到結果-->?
? ?<input type='text' id='fruit' />? ?
?</body>
</html>
2020-09-17
<!DOCTYPE?html> <html> ?<head> ??<title>?事件</title>?? ??<script?type="text/javascript"> ???function?count(){ ??????? ????//獲取第一個輸入框的值 ????var?v1?=?document.getElementById('txt1').value ????//獲取第二個輸入框的值 ????var?v2?=?document.getElementById('txt2').value ????//獲取選擇框的值 ????var?v3?=?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 ????var?res; ????switch(v3){ ????????case?'+':res=parseInt(v1)+parseInt(v2) ????????break; ????????case?'-':res=parseInt(v1)-parseInt(v2) ????????break; ????????case?'*':res=parseInt(v1)*parseInt(v2) ????????break; ????????case?'/':res=parseInt(v1)/parseInt(v2) ????????break; ????} ????//設置結果輸入框的值? ????document.getElementById('fruit').value?=?res ???} ??? ??</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?=?按鈕來調用創建的函數，得到結果-->? ???<input?type='text'?id='fruit'?/>??? ?</body> </html>2020-09-17
<!DOCTYPE html>
<html>
?<head>
? <title> 事件</title> ?
? <script type="text/javascript">
?? function count(){
????? ?
??? //獲取第一個輸入框的值
??? var v1 = document.getElementById('txt1').value
?? ?//獲取第二個輸入框的值
?? ?var v2 = document.getElementById('txt2').value
?? ?//獲取選擇框的值
?? ?var v3 = 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
?? ?var res;
?? ?switch(v3){
?? ???? case '+':res=parseInt(v1)+parseInt(v2)
?? ???? break;
?? ???? case '-':res=parseInt(v1)-parseInt(v2)
?? ???? break;
?? ???? case '*':res=parseInt(v1)*parseInt(v2)
?? ???? break;
?? ???? case '/':res=parseInt(v1)/parseInt(v2)
?? ???? break;
?? ?}
??? //設置結果輸入框的值
??? document.getElementById('fruit').value = res
?? }
? ?
? </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 = 按鈕來調用創建的函數，得到結果-->
?? <input type='text' id='fruit' />? ?
?</body>
</html>