foreach-prop

Array-like methods for objects

:warning: Some javascript implementations don't follow the object key order. Keep that in mind when you use keyOf, lastKeyOf, findKey and find methods.

Content

• Install
• CDN
• Usage
• API
  • forEach
  • map
  • keyOf
  • lastKeyOf
  • includes
  • findKey
  • find
  • filter
  • reduce
  • some
  • every
  • create
  • fill

Install

npm i foreach-prop

CDN

jsDelivr

<script src="https://cdn.jsdelivr.net/npm/foreach-prop@latest/dist/each-prop.umd.js"></script>

for production

<script src="https://cdn.jsdelivr.net/npm/foreach-prop@latest/dist/each-prop.umd.min.js"></script>

more options...

unpkg

<script src="https://unpkg.com/foreach-prop@latest/dist/each-prop.umd.js"></script>

for production

<script src="https://unpkg.com/foreach-prop@latest/dist/each-prop.umd.min.js"></script>

more options...

Usage

example

import { map } from "foreach-prop";

const object = {
  key1: "str",
  key2: 1,
};

const result = map(object, (value, key, extra1) => {
  return key + extra1;
}, " $$");

console.log(result);

{
  key1: "key1 $$",
  key2: "key2 $$",
}

See the API section for more details.

Node.js

const { forEach } = require("foreach-prop");
forEach(object, callback);

Browser

After adding the script tag, eachProp object will be available globally, containing all methods detailed in the API section.

eachProp.forEach(object, callback);

API

forEach

Similar to Array.prototype.forEach. It calls the provided callback function for every key-value-pair in the object. Once initiated there is no way to stop the execution of this function, if you intend to stop the iteration at some point have a look at findKey method.

forEach(object, function callback(value, key, ...extra) => void, ...extra): void;

Any extra argument will be passed down to the callback function.

The callback function inherits the this value from the function call, so if you want a specific this value in your callback function, you can call it using the call method of the Function.prototype.

forEach.call(thisArg, object, callback, ...extra);

map

Similar to Array.prototype.map. It calls the provided callback function for every key-value-pair in the object and returns a new object.

map(object, function callback(value, key, ...extra) => any, ...extra): object;

Any extra argument will be passed down to the callback function.

The callback function inherits the this value from the function call, so if you want a specific this value in your callback function, you can call it using the call method of the Function.prototype.

map.call(thisArg, object, callback, ...extra);

keyOf

Similar to Array.prototype.indexOf. It returns the key of the first value that equals the provided one, or null if not found.

keyOf(object, value): string | null;

lastKeyOf

Similar to Array.prototype.lastIndexOf. It returns the key of the last value that equals the provided one, or null if not found.

lastKeyOf(object, value): string | null;

includes

added in: v0.2.0

Similar to Array.prototype.includes. It returns whether or not a value is present in an object.

includes(object, value): boolean;

findKey

Similar to Array.prototype.findIndex. It calls the provided callback function for every key-value-pair in the object and returns the key once the provided callback function return a truthy value. It returns null if nothing found.

findKey(object, function callback(value, key, ...extra) => any, ...extra): string | null;

Any extra argument will be passed down to the callback function.

The callback function inherits the this value from the function call, so if you want a specific this value in your callback function, you can call it using the call method of the Function.prototype.

findKey.call(thisArg, object, callback, ...extra);

find

added in: v0.1.0

Similar to Array.prototype.find. It calls the provided callback function for every key-value-pair in the object and returns the value once the provided callback function return a truthy value. It returns undefined if nothing found.

find(object, function callback(value, key, ...extra) => any, ...extra): any;

Note that the returned value may be undefined even if the condition is met and the value is undefined.

example

const undef;
// undef is undefined
const object = { key1: undef };
// object.key1 is also undefined

const value = find(object, (val, key) => {
  return key === "key1"
});

console.log(value);
// it logs undefined
// because undef is undefined

undefined

Any extra argument will be passed down to the callback function.

The callback function inherits the this value from the function call, so if you want a specific this value in your callback function, you can call it using the call method of the Function.prototype.

find.call(thisArg, object, callback, ...extra);

filter

Similar to Array.prototype.filter. It calls the provided callback function for every key-value-pair in the object and returns a new object containing the key-value-pairs corresponding to those where the provided callback function returned a truthy value.

filter(object, function callback(value, key, ...extra) => any, ...extra): object;

Any extra argument will be passed down to the callback function.

The callback function inherits the this value from the function call, so if you want a specific this value in your callback function, you can call it using the call method of the Function.prototype.

filter.call(thisArg, object, callback, ...extra);

reduce

Similar to Array.prototype.reduce but with a major difference: if no initial value provided it defaults to undefined.

reduce(object, function callback(current, value, key, ...extra) => any, initial?, ...extra): any;

Any extra argument will be passed down to the callback function.

The callback function inherits the this value from the function call, so if you want a specific this value in your callback function, you can call it using the call method of the Function.prototype.

reduce.call(thisArg, object, callback, initial?, ...extra);

some

added in: v0.2.0

Similar to Array.prototype.some. It returns whether at least one of the key-value-pairs satisfy the provided callback function.

some(object, function callback(value, key, ...extra) => any, ...extra): boolean;

Any extra argument will be passed down to the callback function.

The callback function inherits the this value from the function call, so if you want a specific this value in your callback function, you can call it using the call method of the Function.prototype.

some.call(thisArg, object, callback, ...extra): boolean;

every

added in: v0.2.0

Similar to Array.prototype.every. It returns whether all key-value-pairs satisfy the provided callback function.

every(object, function callback(value, key, ...extra) => any, ...extra): boolean;

Any extra argument will be passed down to the callback function.

The callback function inherits the this value from the function call, so if you want a specific this value in your callback function, you can call it using the call method of the Function.prototype.

every.call(thisArg, object, callback, ...extra): boolean;

create

added in: v2.1.0

Similar to new Array(). It creates a new object with the given keys. If a value is provided, every property will be populated with the given value or undefined otherwise.

create(keys: Array<string | number>, value?: any): object;

example

const object = create(['a', 'b'], true);
console.log(object);

{ a: true, b: true }

fill

added in: v2.1.0

Similar to Array.prototype.fill with a difference, it returns a new object instead of modifying the given one. Every property in the new object will be set to the provided value.

fill(object, value): object;

License

MIT © 2019 Manuel Fernández