vue中mutations常量的这种写法怎么理解？

Question

// mutation-types.js
export const SOME_MUTATION = 'SOME_MUTATION'
// store.js
import Vuex from 'vuex'
import { SOME_MUTATION } from './mutation-types'

const store = new Vuex.Store({
state: { ... },
mutations: {

[SOME_MUTATION] (state) {
  // mutate state
}

}
})

store中的mutations的“[SOME_MUTATION]” 这种写法是啥意思，怎么理解呢？为啥要加个中括号？

Answer 1

ES6 允许字面量定义对象时，用方法二（表达式）作为对象的属性名，即把表达式放在方括号内。

这是es6的写法，转换为es5时这样的

var SOME_MUTATION = 'SOME_MUTATION'
var mutations = {}
mutations[SOME_MUTATION] = function (state) {
    // mutate state
}
...

参考：ECMAScript 6 入门-对象的扩展