for ... in循环用于循环访问对象的属性。
这是语法-
for (variablename in object){
statement or block to execute
}尝试以下示例实现“ for-in”循环。打印网络浏览器的Navigator对象
<html>
<body>
<script>
var aProperty;
document.write("Navigator Object Properties<br /> ");
for(aProperty in navigator) {
document.write(aProperty);
document.write("<br />");
}
document.write ("从循环中退出！");
</script>
</body>
</html>