Set default value of property of object passed on parameter to function

Question

The key difference on this question is I want to keep my property referenced inside the object, not destructured.

export interface MapSettings {
  up: 'trueNorth' | 'runIn' | 'magneticNorth' | 'user';
  rotation?: number;
}

type MapProps = {
  settings: MapSettings;
};

export const Map: FunctionComponent<MapProps> = function Map({
  settings,
}) {

I want to set a default value for settings.rotation but I also want to keep it referenced as settings.rotation because settings has a lot more properties than shown here and I know where the value is coming from.

This is the best answer I can come up with:

export const Map: FunctionComponent<MapProps> = function Map({
  settings: { rotation: settingsRotation = 360, ...settings },
}) {

But it doesn't let me reference settings.rotation with a default value of 360.

just check the property in the first line of your function and set it if it isn't set — bryan60, Apr 09 '20 at 14:31

bryan60 · Accepted Answer · 2020-04-09T14:53:49.117

1

just check it and set it:

export const Map: FunctionComponent<MapProps> = function Map({
  settings,
}) {
  settings.rotation = (settings.rotation || settings.roation === 0) ? settings.rotation : 360

edited Apr 09 '20 at 14:53

answered Apr 09 '20 at 14:33

bryan60

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I was just hoping there would be a way in the constructor. Thanks. – Diesel Apr 09 '20 at 19:46

score 0 · Answer 2 · answered Apr 09 '20 at 14:32

0

Default value is mentioned as { someKey = 'defaultValue' } insead of `{ someKey: 'defaultValue' }

So you can write it like

{
   settings = { rotation: settingsRotation = 360 },
}

answered Apr 09 '20 at 14:32

Zohaib Ijaz

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Set default value of property of object passed on parameter to function

2 Answers2

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