首頁猿問這個(gè)代碼的問題出在哪里，為什么運(yùn)行不出來

這個(gè)代碼的問題出在哪里，為什么運(yùn)行不出來

JavaScript

spl1t 2016-05-12 16:33:40

<!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;?? ?//獲取第二個(gè)輸入框的值??? var b=document.getElementById("txt2").value;?? ?//獲取選擇框的值??? var c=document.getElementById("select").value;??? var sum=" ";?? ?//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??? switch(sum){??????? case "+";??????? sum = parseFloat("txt1") + parseFloat("txt2");??????? break;??????? case "-";??????? sum = parseFloat("txt1") - parseFloat("txt2");??????? break;??????? case "/";??????? sum = parseFloat("txt1") / parseFloat("txt2");??????? break;??????? default;??????? sum = parseFloat("txt1") * parseFloat("txt2");??????? break;??? }??? //設(shè)置結(jié)果輸入框的值 ????? 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' />? ??</body></html>多謝多謝

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<!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;
????//獲取第二個(gè)輸入框的值
????var?b=document.getElementById("txt2").value;
????//獲取選擇框的值
????var?c=document.getElementById("select").value;
????var?sum="?";
????//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
????switch(c){
????????case?"+":
????????sum?=?parseFloat(a)?+?parseFloat(b);
????????break;
????????case?"-":
????????sum?=?parseFloat(a)?-?parseFloat(b);
????????break;
????????case?"/":
????????sum?=?parseFloat(a)?/?parseFloat(b);
????????break;
????????default:
????????sum?=?parseFloat(a)?*?parseFloat(b);
????????break;
????}
????//設(shè)置結(jié)果輸入框的值?
??????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()"/>?<!--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>

1 反對回復(fù) 2016-05-12