嵌套数组到JavaScript中的单个数组

Question

This could be a silly question but, I´m way too new at javascript. And i´m thinking this more than it should.

I´ll set an example:

I have:

animals['Cat', 'Dog'];

and,

mood['Sad' , 'Happy'];

i want:

animalmood[0]=('Cat', 'Happy')
animalmood[1]=('Cat', 'Sad')
animalmood[2]=('Dog', 'Happy')
animalmood[3]=('Dog' 'Sad')

How can this be achieved?

What would be the correct syntax for it? Any help is welcome.

Answer 1

Use nested for loops, pushing each combination of elements into the output array.

 var animals = ['Cat', 'Dog'], mood = ['Sad' , 'Happy'], animalsMood = []; for (var i = 0; i < animals.length; i++) for (var j = 0; j < mood.length; j++) animalsMood.push([animals[i], mood[j]]); console.log(animalsMood); 

Using ES6 in Node.js, you can also take a more functional approach:

 let animals = ['Cat', 'Dog'], mood = ['Sad' , 'Happy'], animalsMood = []; animals.forEach(a => mood.forEach(m => animalsMood.push([a, m]))); console.log(animalsMood); 

Answer 2

A more advanced answer is using reduce function:

const animals = ['Cat', 'Dog'];
const moods = ['Sad' , 'Happy'];


const animalsMood = animals.reduce((result, animal) => 
  result.concat(moods.map(mood => [animal, mood]))
, []);

console.log(JSON.stringify(animalsMood));

Using spread instead of concat

const animals = ['Cat', 'Dog'];
const moods = ['Sad' , 'Happy'];


const animalsMood = animals.reduce((result, animal) => 
  [...result, ...moods.map(mood => [animal, mood])]
, []);

console.log(JSON.stringify(animalsMood));