<!DOCTYPE?html>
<html?xmlns="http://www.w3.org/1999/xhtml">
<head>
????<title></title>
????<script?type="text/javascript">
?????????var?msg="\n函數(shù)的遞歸調(diào)用：\n\n";
?????????//響應(yīng)按鈕的點擊事件
?????????function?Test()
?????????{
?????????????var?result;
?????????????msg+="調(diào)用語句：\n";
?????????????msg+="????result=sum(20);\n";
?????????????msg+="調(diào)用步驟：\n";
?????????????result=sum(20);
?????????????msg+="計算結(jié)果：\n";
?????????????msg+="????result="+result+"\n";
?????????????alert(msg);
?????????}
?????????//計算當(dāng)前步驟加和值
?????????function?sum(m)
?????????{
?????????????if(m==0)
?????????????{
?????????????????return?0;
?????????????}
?????????????else
?????????????{
?????????????????msg+="????result="+m+"+sum("+(m-2)+?");\n";
?????????????????result=m+sum(m-2);
?????????????}
?????????????return?result;
?????????}
????</script>
</head>
<body>
????<input?type="button"?value="測試"?onclick="Test()"/>
</body>
</html>這個遞歸函數(shù)大體的意思我能明白，它在自身中調(diào)用。我有一點不明白，這里的"msg+="調(diào)用語句：\n"。a+=b不是賦值運算嗎？一開始已經(jīng)定義了"var msg="函數(shù)的遞歸調(diào)用:"，那么"msg+="調(diào)用語句"應(yīng)該等價于"msg=msg+"調(diào)用語句"，即"函數(shù)的遞歸調(diào)用:調(diào)用語句"。但是提交后顯示的只是"調(diào)用語句"。如圖求各位老師解惑。
JS的遞歸函數(shù)疑問
天窗的螞蟻
2016-01-22 11:40:22
