Variable MDN Grammar and types: Object literals string literal gives the hoped-for product Integer Unicode escape sequences JavaScript’s Global Namespace Sucks Variables object literal object literals Boolean Boolean gives the expected product 语法和类型 dynamic-typing Boolean MDN are prefixed with Variable identifier Floating-Point Literal MDN Guide for Grammar Variable JavaScript literal object Boolean Integers - Grammar and types - JavaScript | MDN object literal Boolean MDN's introduction to JavaScript, Grammar and Types section