lodash flatten inner array (part of object) and generate as many object based on array length

Question

I have the following Array of Objects. I want to generate as many Objects based on inner 'Y' array length.

var arr = [{x:1,y:[1,2]},{x:2,y:[1,2]}];

Expected Output as follows

var arr = [{x:1,y:1},{x:1,y:2},{x:2,y:1},{x:2,y:2}]

Code I have tried but i could't

arr.forEach(item => {
  return item.y.forEach(inner => {
    return inner;
  })
})

Maheer Ali · Accepted Answer · 2020-02-28 06:33:00Z

4

You can use flatMap() with nested map(). Use flatMap() on the main array and inside that use map() on y property of that object. return an object from inner map() function whose y property will be different and x will be the same

var arr = [{x:1,y:[1,2]},{x:2,y:[1,2]}];
const res = arr.flatMap(({x, y}) => y.map(y => ({x, y})));
console.log(res)

If you don't understand the flatMap below is the version using nested forEach

var arr = [{x:1,y:[1,2]},{x:2,y:[1,2]}];
const res = [];
arr.forEach(a => {
  a.y.forEach(y => {
    res.push({x: a.x, y});
  })
})
console.log(res)

answered Feb 28, 2020 at 6:33

Maheer Ali

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