create an empty object based on pattern of another object

Question

I have an object like this:

const Media = {

    references: { analyze: [432, 5], translate: ["string", false] },
    extensions: { analyze: ["something"], translate: ["something here"] },
    words: ["a word"],
    brackets: [],
    pronounce: [],

    instructions: {
        Expand_Explain: ['Before_First_Movie_Watch_Explain', 'Before_First_Movie_Watch_Explain2', 'Before_First_Movie_Watch_Explain3'],
        Hot_Tutorial: ['1', 'some element', 2],
        Next: [54, true, "string"],
    }
}

And I want to create another object with only instructions property with empty arrays inside:

So this is the desired result:

const NewEmptyMedia = {
    instructions: {
        Expand_Explain: [],
        Hot_Tutorial: [],
        Next: [],
    }
}

Note: the pattern is the same for instructions property always but the number of properties inside instructions is variable.

I created a loop to do this but I need to check multiple if statements and it's really ugly...

Why not just hand code it if it will have not values and only structure? Why do you see a need to refer to a different object when "the pattern is the same for instructions property always"? — Randy Casburn
– Randy Casburn, Commented Feb 18, 2021 at 17:42

Berk Kurkcuoglu · Accepted Answer · 2021-02-18 17:41:59Z

2

You can use a reducer on Object.keys for Media.instructions.

Something like this should suffice:

Object.keys(Media.instructions).reduce((acc, key) => ({...acc, [key]: []}), {});

answered Feb 18, 2021 at 17:41

Berk Kurkcuoglu

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2 Comments

Chris Lear Over a year ago

The result of this is what NewEmptyMedia.instructions should be, I think

Sara Ree Over a year ago

function getNewMedia() {     return {instructions: Object.keys(Media.instructions).reduce((acc, key) => ({...acc, [key]: []}), {})}; }

Chris Lear · Accepted Answer · 2021-02-18 17:48:18Z

0

You can use a class, like this

const Media = {

    references: { analyze: [432, 5], translate: ["string", false] },
    extensions: { analyze: ["something"], translate: ["something here"] },
    words: ["a word"],
    brackets: [],
    pronounce: [],

    instructions: {
        Expand_Explain: ['Before_First_Movie_Watch_Explain', 'Before_First_Movie_Watch_Explain2', 'Before_First_Movie_Watch_Explain3'],
        Hot_Tutorial: ['1', 'some element', 2],
        Next: [54, true, "string"],
    }
}


class EmptyMedia  {
  constructor(template) {
    this.instructions = {};
    for (const arr in template.instructions) {
      this.instructions[arr] = [];
    }  
  }
}

console.log(new EmptyMedia(Media));

answered Feb 18, 2021 at 17:48

Chris Lear

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