Generate smaller arrays within a main array

Question

Generate smaller arrays within a main array

What is the most efficient method for creating sub-arrays from an array? I have an array of objects like this:

bigArray = [
    {
        id: 1,
        name: "Marc",
        age: 29
    },
    {
        id: 2,
        name: "Caroline",
        age: 27
    },
    {
        id: 3,
        name: "John",
        age: 30
    }];

I want to generate 3 sub-arrays:

ids = [1, 2, 3]
names = ["Marc", "Caroline", "John"]
ages = [29, 27, 30]

I've attempted using nested "for" loops and experimented with the map() method, but I'm not convinced it's the most efficient way. Especially since each object may have multiple parameters (such as last name, city, car...)

javascript arrays typescript

Answer 1

Answer №1

If all the objects in the array have the same keys, here is one way to approach it:

bigArray = [
    {
        id: 1,
        name: "Marc",
        age: 29
    },
    {
        id: 2,
        name: "Caroline",
        age: 27
    },
    {
        id: 3,
        name: "John",
        age: 30
    }];

let output = {}

Object.keys(bigArray[0]).forEach( key => {
output[key+"s"] = bigArray.map( obj => obj[key] )
})

// Or as a one-liner, to impress your friends
Object.keys(bigArray[0]).forEach( key => output[key+"s"] = bigArray.map( obj => obj[key] ))

console.log(output)

You can then access the data using output.names, output.ages

Answer 2

If all the objects in the array have the same keys, here is one way to approach it:

bigArray = [
    {
        id: 1,
        name: "Marc",
        age: 29
    },
    {
        id: 2,
        name: "Caroline",
        age: 27
    },
    {
        id: 3,
        name: "John",
        age: 30
    }];

let output = {}

Object.keys(bigArray[0]).forEach( key => {
output[key+"s"] = bigArray.map( obj => obj[key] )
})

// Or as a one-liner, to impress your friends
Object.keys(bigArray[0]).forEach( key => output[key+"s"] = bigArray.map( obj => obj[key] ))

console.log(output)

You can then access the data using output.names, output.ages

Generate smaller arrays within a main array

Answer №1

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