如何有效地匹配两个不同的javascript对象上的id并将它们合并在一起？

Question

This is somewhat similar to a join table. I have two different javascript objects. One of these objects is an array of objects, where one of the properties in that object is an array of ids. These ids map directly to another array of javascript objects.

ex.

users = [{
  name: 'Bob',
  birthday: '01-02-1990',
  favorite_color_ids: ['2', '4', '6']
},
{
....etc

}]

colors: [{
  id: 2,
  name: 'red',
  hex_val: '#FF0000'
},
{
  ...etc
}]

I want to create another property on each object in the users array, called 'favorite_color_names'. What would be the most efficient way to do this? Currently have many nested _.each operations.

Answer 1

Expanding on my comment above, if you need to access the colors by ID frequently, but can't change the structure from an Array, I'd just go ahead and dynamically create an object structure that references each color by ID.

var colors_by_id = {}

colors.forEach(color) {
    colors_by_id[color.id] = color
})

Then you can make your arrays of names if you wish for each user (though it would seem less important since you can now easily get it on the fly) .

users.forEach(user) {
    user.favorite_color_names = user.favorite_color_ids.map(function(id) {
        return colors_by_id[id].name
    })
})