# foreach-prop
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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](#install)
* [CDN](#cdn)
* [Usage](#usage)
* [API](#api)
* [forEach](#foreach)
* [map](#map)
* [keyOf](#keyof)
* [lastKeyOf](#lastkeyof)
* [includes](#includes)
* [findKey](#findkey)
* [find](#find)
* [filter](#filter)
* [reduce](#reduce)
* [some](#some)
* [every](#every)
* [create](#create)
* [fill](#fill)
## Install
```bash
npm i foreach-prop
```
## CDN
### jsDelivr
```html
```
**_for production_**
```html
```
*[more options...](https://www.jsdelivr.com/package/npm/foreach-prop?version=latest)*
### unpkg
```html
```
**_for production_**
```html
```
*[more options...](https://unpkg.com/foreach-prop@latest/)*
## Usage
**_example_**
```javascript
import { map } from "foreach-prop";
const object = {
key1: "str",
key2: 1,
};
const result = map(object, (value, key, extra1) => {
return key + extra1;
}, " $$");
console.log(result);
```
```console
{
key1: "key1 $$",
key2: "key2 $$",
}
```
*See the [API section](#api) for more details.*
### Node.js
```javascript
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](#api).*
```javascript
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`](#findkey) *method.*
```typescript
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`*.*
```javascript
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.*
```typescript
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`*.*
```javascript
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.*
```typescript
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.*
```typescript
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.*
```typescript
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.*
```typescript
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`*.*
```javascript
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.*
```typescript
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_**
```javascript
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
```
```console
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`*.*
```javascript
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.*
```typescript
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`*.*
```javascript
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`*.*
```typescript
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`*.*
```javascript
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.*
```javascript
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`*.*
```javascript
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.*
```javascript
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`*.*
```javascript
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.*
```typescript
create(keys: Array, value?: any): object;
```
**_example_**
```typescript
const object = create(['a', 'b'], true);
console.log(object);
```
```bach
{ 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.*
```typescript
fill(object, value): object;
```
## License
[MIT](LICENSE) © 2019 [Manuel Fernández](https://github.com/manferlo81)