selectFirst

143 bytes

Usage

The selectFirst function combines the functionality of find and map operations on an array. It iterates through the array, applying a mapper function to each element, and returns the first mapped value that satisfies a given condition. If no condition is provided, it returns the first non-nullish mapped value.

This function is particularly useful when you need to find and transform an element in a single operation, potentially saving time and improving code readability.

Key features:

• Short-circuits on the first element that satisfies the condition
• Allows for separate mapping and condition functions
• Returns undefined if no element satisfies the condition or if the array is empty/nullish

import * as _ from 'radashi'

// Find the first even number and double it
_.selectFirst(
  [1, 3, 4, 6, 8],
  x => x * 2,
  x => x % 2 === 0,
)
// => 8

// Find the first non-empty string and convert to uppercase
_.selectFirst(
  ['', null, 'hello', 'world'],
  s => s?.toUpperCase(),
  s => s !== null && s !== '',
)
// => 'HELLO'

// Find the first object with a specific property and extract a value
const users = [
  { id: 1, name: 'Alice', age: 30 },
  { id: 2, name: 'Bob', age: 25 },
  { id: 3, name: 'Charlie', age: 35 },
]
_.selectFirst(
  users,
  user => user.name,
  user => user.age > 30,
)
// => 'Charlie'

// Using default condition (non-nullish)
_.selectFirst([null, undefined, 0, '', false, 'found'], x => x)
// => 0