代码示例：

<!DOCTYPE html>
<html>
    <head>
        <meta charset="utf-8">
        <title></title>
    </head>
    <body>
        <script>
            var obj ={a:99,b:66,c:"你好"}
            console.log(obj)
            // 增，改
            // obj.b = 33
            // obj["c"] =44
            // console.log(obj)
            // 删
            // delete obj.b
            // delete obj["c"]
            // console.log(obj)
            // 查
            console.log(obj.a)
            console.log(obj["c"])
        </script>
    </body>
</html>