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哪里錯(cuò)了,求大神

JavaScript

小小小小霸王 2016-09-29 11:55:20

<!DOCTYPE?html> <html> ?<head> ?????<meta?charset="utf-8"?/> ??<title>?事件</title>?? ??<script?type="text/javascript"> ???function?count(){ ??????????? ????????????var?a=parseInt(document.getElementById("txt1").value;); ????????var?b=parseInt(document.getElementById("txt2").value;); ????????var?box=document.getElementById("select").value; ????????var?sum; ????????switch(box){ ????????????case?"+": ????????????sum=a+b; ????????????return?sum; ????????????break; ????????????case?"-": ????????????sum=a-b; ????????????return?sum; ????????????break; ????????????case?"*": ????????????sum=a*b; ????????????return?sum; ????????????break; ????????????case?"/": ????????????sum=a/b; ????????????return?sum; ????????????break; ????????}; ????????document.getElementById("fruit").value=sum; ???}; ??</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"?value=""/>??? ?</body> </html>

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1 回答

已采納

慕用0418482

TA貢獻(xiàn)98條經(jīng)驗(yàn) 獲得超15個(gè)贊

<!DOCTYPE?html>
<html>
?<head>
?????<meta?charset="utf-8"?/>
??<title>?事件</title>??
??<script?type="text/javascript">
???function?count(){??
????????var?a=parseInt(document.getElementById("txt1").value);
????????var?b=parseInt(document.getElementById("txt2").value);
????????var?box=document.getElementById("select").value;
????????var?sum;
????????switch(box){
????????????case?"+":?sum=a+b?;?break;
????????????case?"-":?sum=a-b?;?break;
????????????case?"*":?sum=a*b?;?break;
????????????case?"/":?sum=a/b?;?break;
????????};
????????document.getElementById("fruit").value=sum;
????????console.log(sum)
???};
??</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(guò)?=?按鈕來(lái)調(diào)用創(chuàng)建的函數(shù)，得到結(jié)果-->?
???<input?type='text'?id="fruit"?value=""/>???
?</body>
</html>

不用return

1 反對(duì) 回復(fù) 2016-09-29