For example in redux actions, I've seen in someone's code:
export const updateMessage = text => {
return (dispatch) => {
dispatch(updateChatMessage(text))
}
}
and:
const updateChatMessage = text => ({
type: types.someActionType,
text
})
it seems to function as an imply a return
but I thought that was already implied in an arrow functions brackets following the fat arrow.
What do the parenthesis ({...})
do? are they necessary? Is there an alternate way to accomplish the same thing?
when you write myFunction = value => ({prop: value})
it return the object {prop: value}
, in this case {}
are object delimiter and not 'function delimiter'
const updateChatMessage = text => ({
type: types.someActionType,
text
})
another eg :
when you want to multiply by two each elem of an array you can write :
array.map(elem => {return elem * 2})
or
array.map(elem => elem * 2)
//same result
and if you want an eg with ()
that wrap an object litteral :
let array = [{val: 2},
{val: 4},
{val: 8},
{val: 16}];
let output = array.map( ({val}) => ({val: val*2}) );
console.log(output);
If you wrap the brackets with parenthesis you are making your function return an object literal (thus you don't need the return keyword). If you don't use parenthesis you have to use the return keyword.
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