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| /** | |
| * Creates a keyed JS object from an array, given a function to produce the keys | |
| * for each value in the array. | |
| * | |
| * This provides a convenient lookup for the array items if the key function | |
| * produces unique results. | |
| * ```ts | |
| * const phoneBook = [ | |
| * { name: 'Jon', num: '555-1234' }, | |
| * { name: 'Jenny', num: '867-5309' } | |
| * ] | |
| * | |
| * const entriesByName = keyMap( | |
| * phoneBook, | |
| * entry => entry.name | |
| * ) | |
| * | |
| * // { | |
| * // Jon: { name: 'Jon', num: '555-1234' }, | |
| * // Jenny: { name: 'Jenny', num: '867-5309' } | |
| * // } | |
| * | |
| * const jennyEntry = entriesByName['Jenny'] | |
| * | |
| * // { name: 'Jenny', num: '857-6309' } | |
| * ``` | |
| */ | |
| export function keyMap(list, keyFn) { | |
| const result = Object.create(null); | |
| for (const item of list) { | |
| result[keyFn(item)] = item; | |
| } | |
| return result; | |
| } | |