ES6 function definition with object destructuring with defaults

Question

So I have this function that has the following JSDoc

/**
 * Initializes a new game, this means creating a new map and centering on the
 * playerbase
 *
 * @param {object} param1
 * @param {number} param1.seed
 * */

Currently I have this as the function definition

initNewGame({ seed }) {}

But I would like to have a default value for seed, which is randomInt(0, 100000). How can I achieve this.

when you are defining the function params use `initNewGame({seed: randomInt(0, 100000)})` — about14sheep, Nov 14 '21 at 20:31
@about14sheep I did try this but it didnt work for some reason — Daan Breur, Nov 14 '21 at 20:33
@about14sheep - the your syntax is incorrect of the key:value pair. — Randy Casburn, Nov 14 '21 at 20:34
if you pass something into the function for the param seed it will set the value to that — about14sheep, Nov 14 '21 at 20:34
`function initNewGame({ seed = randomInt(0, 100000) } = {}) { ... }` If you want to be able to pass it without the parameter completely. — Ivar, Nov 14 '21 at 20:34
Passing a function is another option. Set a default fn ref and call it in `initNewGame`, or pass in a different one. — Dave Newton, Nov 14 '21 at 20:44
@Ivar Your answer did do the trick! Thank you. If you can make it a SO Answer ill mark it answer for other people to find — Daan Breur, Nov 14 '21 at 20:54

Rensykes · Answer 1 · 2021-11-14T20:54:24.417

You could do the following:

function initNewGame(params, seed = randomInt(0, 100000)) {
   //body of the function
}

this can then be called like this:

let params = {}
let seed = 4124;
initNewGame(params);
//or 
initNewGame(params, seed);

Unfortunately this means that the JSDoc should change accordingly, since seed is not a property of props anymore.

EDIT: another thing you can do is:

function initNewGame(params = {anyvalue: "hello", seed: getRandomInt(1000)}) {
  console.log(params.seed)
}

initNewGame();
//or
initNewGame({anyvalue: "hello in call", seed: 1000});

bryan60 · Answer 2 · 2021-11-14T20:44:41.370

0

function initNewGame({seed} = {}) {
  seed = seed !== undefined ? seed : randomInt(0, 100000);
  // the rest
}

edited Nov 14 '21 at 20:44

answered Nov 14 '21 at 20:32

bryan60

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ES6 function definition with object destructuring with defaults

2 Answers2