I am following the redux tutorial and having a hard time understanding the following code

export function addTodo(text) {
      return { type: ADD_TODO, text }
    }

So the function above returns the object { type: ADD_TODO, text } and there are two things that confuse me.

1. what is the value of this object associated with the key text. If this value is undefined, then why not just return { type: ADD_TODO} instead.

2. If text is a string, then shouldn't it be { type: ADD_TODO, [text]: *some value* } instead?

Moreover, there are other functions like

function toggleTodo(index) {
      return { type: TOGGLE_TODO, index }
    }
function setVisibilityFilter(filter) {
      return { type: SET_VISIBILITY_FILTER, filter }
    }

Can someone explain this syntax to me?

I am following the redux tutorial https://redux.js/basics/actions and having a hard time understanding the following code

export function addTodo(text) {
      return { type: ADD_TODO, text }
    }

So the function above returns the object { type: ADD_TODO, text } and there are two things that confuse me.

1. what is the value of this object associated with the key text. If this value is undefined, then why not just return { type: ADD_TODO} instead.

2. If text is a string, then shouldn't it be { type: ADD_TODO, [text]: *some value* } instead?

Moreover, there are other functions like

function toggleTodo(index) {
      return { type: TOGGLE_TODO, index }
    }
function setVisibilityFilter(filter) {
      return { type: SET_VISIBILITY_FILTER, filter }
    }

Can someone explain this syntax to me?

• javascript
• redux
• javascript-objects

Share Improve this question Follow asked Dec 24, 2019 at 2:37 PhantomPhantom 44311 gold badge66 silver badges1414 bronze badges 1

• { type: ADD_TODO, text } is the es6 shorthand for { type: ADD_TODO, text:text } given a variable text. – Mark Commented Dec 24, 2019 at 2:39

Add a ment  | 

1 Answer 1

Sorted by: Reset to default 8

They're using ES6 Shorthand property names - If the intended key name is the same as the variable, then you can simply pass the variable

let name = 'Jared';
let age = 19;
let literate = false;

let obj = {
  name,
  age,
  literate
}

/* Is the same as...
let obj = {
  'name': name,
  'age': age,
  'literate': literate
}
*/

console.log(obj);