根据另一个 object 的模式创建一个空的 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...

Answer 1

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]: []}), {});

Answer 2

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));