如下，关于javascript中数组的自定义属性，应该怎么理解

var ary = ["a", "b", "c"]; ary.name = "test"; console.log(ary); // ["a", "b", "c", name: "test"] console.log(ary.length); // 3 console.log(Array.isArray(ary)); // true  ary.forEach(v => console.log(v)); // 依次打印 a b c console.log(ary.name); // "test"