Using Bind with an array in a function

ion-v · December 22, 2018, 6:04pm

Hello, can someone explain what happens in the line with “bind” (the state.colors returns an array in this example):
const print = compose(
list = console.log(list),
titles = titles.join(", "),
map = map(c=c.title),
colors = colors.map.bind(colors),
state = state.colors
)

this is the array:
Capture

This is the original code:

github.com

MoonHighway/learning-react/blob/master/chapter-08/03-action-creators/02-action-creators.html

<!DOCTYPE html>
<html>
<head>
    <meta name="viewport" content="minimum-scale=1.0, width=device-width, maximum-scale=1.0, user-scalable=no"/>
    <meta charset="utf-8">
    <script src="https://unpkg.com/redux@3.7.2/dist/redux.min.js"></script>
    <script src="https://unpkg.com/babel-standalone@6.15.0/babel.min.js"></script>
    <script src="https://unpkg.com/node-uuid@1.4.7/uuid.js"></script>
    <title>Redux</title>
</head>
<body>
<div id="react-container"></div>
  <script type="text/babel">

      const { createStore, combineReducers, compose } = Redux
      const { v4 } = uuid

      const color = (state = {}, action) => {
          switch (action.type) {
              case "ADD_COLOR":

This file has been truncated. show original

you can see the code working in the console of this page:
https://rawgit.com/MoonHighway/learning-react/master/chapter-08/03-action-creators/02-action-creators.html
Thank you

JohnnyBizzel · December 24, 2018, 12:30am

This is what bind does: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_objects/Function/bind

DanCouper · December 24, 2018, 1:52pm

The first argument to bind is the this value. So I assume that the colors is going to be used somewhere else, and needs to retain the value it has in the place it is defined (in that chunk of code above) rather than the place it is called. There is no context to any of the code you posted, so can’t tell you anything specific.

ion-v · December 24, 2018, 8:52pm

Thanks for the answers.
I’ve edited the original question to show the entire code (github) and it’s result (that can be seen in the devtools console).
After reading your answers and the links, I get the general idea but not how it applies in this specific case. If I understand correctly, the state=>state.colors returns an array, but don’t all arrays have the map method? Also, shouldn’t arrow function solve this problem? Why would you need the bind then (the code doesn’t work without the using bind on the color argument, so probably it has to be very important).
Thanks for your time