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<!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(shè)置結(jié)果輸入框的值?

? ?}

??

? </script>?

?</head>?

?<body>

? ?<input type='text' id='txt1' />?

? ?<select id='select'>

? ?</select>

? ?<input type='text' id='txt2' />?

? ?<input type='button' value=' = ' onclick="count()"/> ?

? ?<input type='text' id='fruit' />? ?

?</body>

</html>

成事不足先生

2020-07-31

源自：JavaScript進階篇 6-11

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2 回答

慕勒2524652
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(shè)置結(jié)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(diào)用創(chuàng)建的函數(shù)，得到結(jié)果-->?
???<input?type='text'?id='fruit'?/>???
?</body>
</html>

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慕勒2524652
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(shè)置結(jié)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()" /> 
?? <input type='text' id='fruit' />? ?
?</body>
</html>