CODEWITHSUNDEEP
typescript
user133688
user133688

Reputation: 7064

What is the meaning of an object param in a function signature?

What is the meaning of an object param in a function signature? I came across this code snippet, and I'm not sure what's going on here. 

export const items = (state: any = [], {type, payload}) => {
  case (type) {
    ...
  }
};

I don't understand the {type, payload} in the function signature.

Upvotes: 1

Views: 55

Answers (1)

Seamus
Seamus

Reputation: 4829

This is an example of destructuring.

You can see what this:

let items = (state: any = [], {type, payload}) => {

};

compiles to on the TypeScript playground:

var items = function (state, _a) {
     if (state === void 0) { state = []; }
     var type = _a.type, payload = _a.payload;
};

And from that I can infer that it means that the second parameter of the function will be an object with a property called "type", and another property called "payload". Further, I will be able to refer to "type" and "payload" directly in my function body:

let items = (state: any = [], {type, payload}) => {
    console.log(type);
    console.log(payload);
};

let myobj = {
    payload: "blue",
    type: "no-type"
}

items(null, myobj);

Upvotes: 3

Related Questions