定义字典
a = {"k1":"v1","k2":"v2",}; Object {k1: "v1", k2: "v2"}
javascript字典取值和python一样
a Object {k1: "v1", k2: "v2"} a["k1"] "v1" a["k2"] "v2"
其实javascript 没有字典 javascript字典叫做对象