pick

Pick only the desired properties from an object

Usage

Given an object and a list of keys in the object, returns a new object with only the given keys.

import * as 
import _
_ from 'radashi'

const 
const fish: {
    name: string;
    weight: number;
    source: string;
    brackish: boolean;
}
fish = {
  
name: string
name: 'Bass',
  
weight: number
weight: 8,
  
source: string
source: 'lake',
  
brackish: boolean
brackish: false,
}

import _
_.
pick<{
    name: string;
    weight: number;
    source: string;
    brackish: boolean;
}, ("name" | "source")[]>(obj: {
    name: string;
    weight: number;
    source: string;
    brackish: boolean;
}, filter: ("name" | "source")[]): Pick<...>
export pick
Pick a list of properties from an object into a new object.
⚠️ When used with a predicate function, pick is potentially
unsafe, because of partial type matching performed by TypeScript.
If you pass an object with more properties than its TypeScript type
has listed, the value and key parameter types of your callback
will be inaccurate.
@see ― https://radashi.js.org/reference/object/pick
@example 
const a = { a: 1, b: 2, c: 3 }

pick(a, ['a', 'c'])
// => { a: 1, c: 3 }

pick(a, (value, key) => value > 1)
// => { b: 2, c: 3 }
@version ― 12.1.0
pick(
const fish: {
    name: string;
    weight: number;
    source: string;
    brackish: boolean;
}
fish, ['name', 'source']) // => { name, source }

Predicate function

The pick function can also accept a predicate function as the filter argument. This allows for more complex filtering logic beyond simple key inclusion or exclusion.

import * as 
import _
_ from 'radashi'

const 
const source: {
    a: number;
    b: number;
    c: number;
    d: number;
}
source = { 
a: number
a: 1, 
b: number
b: 2, 
c: number
c: 3, 
d: number
d: 4 }

import _
_.
pick<{
    a: number;
    b: number;
    c: number;
    d: number;
}, (value: number, key: "a" | "b" | "c" | "d") => boolean>(obj: {
    a: number;
    b: number;
    c: number;
    d: number;
}, filter: (value: number, key: "a" | "b" | "c" | "d") => boolean): Pick<...>
export pick
Pick a list of properties from an object into a new object.
⚠️ When used with a predicate function, pick is potentially
unsafe, because of partial type matching performed by TypeScript.
If you pass an object with more properties than its TypeScript type
has listed, the value and key parameter types of your callback
will be inaccurate.
@see ― https://radashi.js.org/reference/object/pick
@example 
const a = { a: 1, b: 2, c: 3 }

pick(a, ['a', 'c'])
// => { a: 1, c: 3 }

pick(a, (value, key) => value > 1)
// => { b: 2, c: 3 }
@version ― 12.1.0
pick(
const source: {
    a: number;
    b: number;
    c: number;
    d: number;
}
source, (
value: number
value, 
key: "a" | "b" | "c" | "d"
key) => {
  return 
value: number
value % 2 === 0 // Include only even values
})
// => { b: 2, d: 4 }

Unsafe predicate function

// Example demonstrating potential inaccuracy in `key` and `value` types within `_.pick` callback
import * as 
import _
_ from 'radashi'

interface 
interface User
User {
  
User.name: string
name: string
  
User.age: number
age: number
}

function 
function getUserDetails(user: User): Pick<User, keyof User>
getUserDetails(
user: User
user: 
interface User
User) {
  return 
import _
_.
pick<User, _.KeyFilter<User, keyof User>>(obj: User, filter: _.KeyFilter<User, keyof User>): Pick<User, keyof User>
export pick
Pick a list of properties from an object into a new object.
⚠️ When used with a predicate function, pick is potentially
unsafe, because of partial type matching performed by TypeScript.
If you pass an object with more properties than its TypeScript type
has listed, the value and key parameter types of your callback
will be inaccurate.
@see ― https://radashi.js.org/reference/object/pick
@example 
const a = { a: 1, b: 2, c: 3 }

pick(a, ['a', 'c'])
// => { a: 1, c: 3 }

pick(a, (value, key) => value > 1)
// => { b: 2, c: 3 }
@version ― 12.1.0
pick(
user: User
user, (
value: string | number
value, 
key: keyof User
key) => {
    // TypeScript believes `key` is 'name' | 'age', but at runtime
    // it could be 'email'
    if (
key: keyof User
key === 'name' || 
key: "age"
key === 'age') {
      
var console: Console
The console module provides a simple debugging console that is similar to the
JavaScript console mechanism provided by web browsers.
The module exports two specific components:

A Console class with methods such as console.log(), console.error() and console.warn() that can be used to write to any Node.js stream.
A global console instance configured to write to process.stdout and
process.stderr. The global console can be used without importing the node:console module.

Warning: The global console object's methods are neither consistently
synchronous like the browser APIs they resemble, nor are they consistently
asynchronous like all other Node.js streams. See the note on process I/O for
more information.
Example using the global console:
console.log('hello world');
// Prints: hello world, to stdout
console.log('hello %s', 'world');
// Prints: hello world, to stdout
console.error(new Error('Whoops, something bad happened'));
// Prints error message and stack trace to stderr:
//   Error: Whoops, something bad happened
//     at [eval]:5:15
//     at Script.runInThisContext (node:vm:132:18)
//     at Object.runInThisContext (node:vm:309:38)
//     at node:internal/process/execution:77:19
//     at [eval]-wrapper:6:22
//     at evalScript (node:internal/process/execution:76:60)
//     at node:internal/main/eval_string:23:3

const name = 'Will Robinson';
console.warn(`Danger ${name}! Danger!`);
// Prints: Danger Will Robinson! Danger!, to stderr
Example using the Console class:
const out = getStreamSomehow();
const err = getStreamSomehow();
const myConsole = new console.Console(out, err);

myConsole.log('hello world');
// Prints: hello world, to out
myConsole.log('hello %s', 'world');
// Prints: hello world, to out
myConsole.error(new Error('Whoops, something bad happened'));
// Prints: [Error: Whoops, something bad happened], to err

const name = 'Will Robinson';
myConsole.warn(`Danger ${name}! Danger!`);
// Prints: Danger Will Robinson! Danger!, to err
@see ― source
console.
Console.log(message?: any, ...optionalParams: any[]): void
Prints to stdout with newline. Multiple arguments can be passed, with the
first used as the primary message and all additional used as substitution
values similar to printf(3)
(the arguments are all passed to util.format()).
const count = 5;
console.log('count: %d', count);
// Prints: count: 5, to stdout
console.log('count:', count);
// Prints: count: 5, to stdout
See util.format() for more information.
@since ― v0.1.100
log(
key: keyof User
key, '=', 
value: string | number
value)
    } else {
      // TypeScript believes this will never run, but it does.
      
var console: Console
The console module provides a simple debugging console that is similar to the
JavaScript console mechanism provided by web browsers.
The module exports two specific components:

A Console class with methods such as console.log(), console.error() and console.warn() that can be used to write to any Node.js stream.
A global console instance configured to write to process.stdout and
process.stderr. The global console can be used without importing the node:console module.

Warning: The global console object's methods are neither consistently
synchronous like the browser APIs they resemble, nor are they consistently
asynchronous like all other Node.js streams. See the note on process I/O for
more information.
Example using the global console:
console.log('hello world');
// Prints: hello world, to stdout
console.log('hello %s', 'world');
// Prints: hello world, to stdout
console.error(new Error('Whoops, something bad happened'));
// Prints error message and stack trace to stderr:
//   Error: Whoops, something bad happened
//     at [eval]:5:15
//     at Script.runInThisContext (node:vm:132:18)
//     at Object.runInThisContext (node:vm:309:38)
//     at node:internal/process/execution:77:19
//     at [eval]-wrapper:6:22
//     at evalScript (node:internal/process/execution:76:60)
//     at node:internal/main/eval_string:23:3

const name = 'Will Robinson';
console.warn(`Danger ${name}! Danger!`);
// Prints: Danger Will Robinson! Danger!, to stderr
Example using the Console class:
const out = getStreamSomehow();
const err = getStreamSomehow();
const myConsole = new console.Console(out, err);

myConsole.log('hello world');
// Prints: hello world, to out
myConsole.log('hello %s', 'world');
// Prints: hello world, to out
myConsole.error(new Error('Whoops, something bad happened'));
// Prints: [Error: Whoops, something bad happened], to err

const name = 'Will Robinson';
myConsole.warn(`Danger ${name}! Danger!`);
// Prints: Danger Will Robinson! Danger!, to err
@see ― source
console.
Console.log(message?: any, ...optionalParams: any[]): void
Prints to stdout with newline. Multiple arguments can be passed, with the
first used as the primary message and all additional used as substitution
values similar to printf(3)
(the arguments are all passed to util.format()).
const count = 5;
console.log('count: %d', count);
// Prints: count: 5, to stdout
console.log('count:', count);
// Prints: count: 5, to stdout
See util.format() for more information.
@since ― v0.1.100
log('Unexpected key:', 
key: never
key)
    }
  })
}

// At runtime, the function may receive an object with more properties
const 
const runtimeUser: {
    name: string;
    age: number;
    email: string;
}
runtimeUser = {
  
name: string
name: 'John',
  
age: number
age: 30,
  // This property is not listed in the User type:
  
email: string
email: 'john@example.com',
}

function getUserDetails(user: User): Pick<User, keyof User>
getUserDetails(
const runtimeUser: {
    name: string;
    age: number;
    email: string;
}
runtimeUser)
// Logs the following:
//     name = John
//     age = 30
//     Unexpected key: email