Mapping array values with constructors
Syntactic sugar on the Array prototype’s map function and type constructors being functions allow us to quickly map values from one type to another.
Read fire tipQuickly finding objects in large arrays
If you identify objects in an array by a unique property, turn the array into a lookup object. The unique property becomes a key, giving you access to the objects without having to search for them in the array first.
// this array holds objects that all have name- and type-properties
const array = [
{ name: 'Bulbasaur', type: 'Grass/Poison' },
{ name: 'Charmander', type: 'Fire' },
{ name: 'Squirtle', type: 'Water' },
{ name: 'Pikachu', type: 'Electric' }
]
// to get the type for a name, we need to .find() the element first
array.find(pokemon => pokemon.name === 'Charmander').type
// ⇒ 'Fire'
// this lookup object uses the unique names as keys
const object = {
'Bulbasaur': { name: 'Bulbasaur', type: 'Grass/Poison' },
'Charmander': { name: 'Charmander', type: 'Fire' },
'Squirtle': { name: 'Squirtle', type: 'Water' },
'Pikachu': { name: 'Pikachu', type: 'Electric' }
}
// lookups work with bracket notation, which is faster than .find()
object['Charmander'].type
// ⇒ 'Fire'