Optimize _.defaults so that it doesn't access property values it doesn't need to

[battmanz]

Suppose I have some config object that must be initialized. Well, at least some of the properties must be initialized -- some do not.

const initializableConfig = {
  initialize(data) {
    this.data = data;
  },
  get a() {
    return this.data.a;
  },
  get b() {
    return this.data.b;
  }
  c: "I don't need to be initialized"
};

I would like to be able to use the initializableConfig as a default at all times (even before it's initialized). I should be fine to do so as long as I override the properties that must be initialized.

const config = {
  a: 'apple',
  b: 'banana'
};

const finalConfig = _.defaults({}, config, initializableConfig); // Error! Cannot read property 'a' of undefined

Since config defines a and b, I see no reason why those properties need to be accessed on the initializableConfig. Currently they are and an error is being thrown.

Couldn't _.defaults be optimized to avoid this error?

[jdalton]

Yep, that's doable. Thanks!

[battmanz]

Wow, that was fast! Thank you!

[battmanz]

@jdalton Do you know when the next release will be?

[jdalton]

It'll be in our v5 release, so expect a delay.

[lock]

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