* [1.1](https://github.com/yuche/javascript#1.1) **基本类型**: 直接存取基本类型。 * `字符串` * `数值` * `布尔类型` * `null` * `undefined` ~~~ const foo = 1; let bar = foo; bar = 9; console.log(foo, bar); // => 1, 9 ~~~ * [1.2](https://github.com/yuche/javascript#1.2) **复制类型**: 通过引用的方式存取复杂类型。 * `对象` * `数组` * `函数` ~~~ const foo = [1, 2]; const bar = foo; bar[0] = 9; console.log(foo[0], bar[0]); // => 9, 9 ~~~