javascript - Merging Arrays of Objects by Key/Values -

i have 2 separate arrays of objects need merge based if specific key value matches. might make more sense after analyzing data:

array 1

let categories = [     { id: 5, slug: 'category-5', items: []  },     { id: 4, slug: 'category-4', items: []  },     { id: 3, slug: 'category-3', items: []  }, ] 

array 2

let items = [     { id: 5, data: [{ title: 'item title', description: 'item description' }] },     { id: 5, data: [{ title: 'item title 2', description: 'item description 2' }] },     { id: 4, data: [{ title: 'item title 4', description: 'item description 4' }] }, ] 

expected output

let mergedoutput = [     { id: 5, slug: 'category-5',          items: [             { title: 'item title', description: 'item description' },             { title: 'item title 2', description: 'item description 2' }         ]     },     { id: 4, slug: 'category-4',         items: [             { title: 'item title 4', description: 'item description 4' },         ]     },     { id: 3, slug: 'category-3', items: []  }, ] 

so....i need add array 2 array 1 if id's match. array 1 stay same, if array 2 matches, items property of array 1 (empty) replaced data property of array 2

i know pretty basic / , redundant question, can't find resources use case / object structure.

i able group arrays lodash -- if there similar solution library -- good! or direction suffice.

thanks in advance!

you can loop first array , use filter objects same id current element , add items current object.

let categories = [      { id: 5, slug: 'category-5', items: []  },      { id: 4, slug: 'category-4', items: []  },      { id: 3, slug: 'category-3', items: []  },  ]    let items = [      { id: 5, data: [{ title: 'item title', description: 'item description' }] },      { id: 5, data: [{ title: 'item title 2', description: 'item description 2' }] },      { id: 4, data: [{ title: 'item title 4', description: 'item description 4' }] },  ]    categories.foreach(function(e) {    var = items.filter(a => a.id == e.id).map(a => a.data);    e.items = i;  })    console.log(categories)