CODEWITHSUNDEEP
javascriptecmascript-6
swdev
swdev

Reputation: 5157

What does `type` means in the following JavaScript snippet?

I am (totally) newbie in JavaScript (or to be exact, in ES6), and using this article to guide me. What I want to ask is the second line. What does type means in that import statement? Is type a keyword in JavaScript? Because if understand it correctly, I know that the line: import type { fromJS } from 'immutable', is meant to import fromJS function from package immutable (I come from Python background).

I also see that in the line action: {type: string, payload: any }) => {, there is a type parameter. But I guess that is just coincidence, right? 

import Immutable from 'immutable'
import type { fromJS } from 'immutable'

import { SAY_HELLO } from '../action/hello'

const initialState = Immutable.fromJS({
  message: 'Initial message',
})

const helloReducer = (state: fromJS = initialState, action: {type: string, payload: any }) => {
  switch(action.type) {
    case SAY_HELLO:
      return state.set('message', action.payload)
    default:
      return state
  }
}

export default helloReducer

dd

Upvotes: 0

Views: 46

Answers (1)

Fareed Alnamrouti
Fareed Alnamrouti

Reputation: 32174

the article you refer to is using the flow type library you can read more about it here: https://flow.org/

Upvotes: 1

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