# date-helper-js
> functions for working with date
[](https://www.npmjs.com/package/date-helper-js)
[](https://www.jsdelivr.com/package/npm/date-helper-js)
## Table of Contents
- [Quick start](#quick-start)
- [Install](#install)
- [Initialization](#initialization)
- [Methods](#methods)
- [getMonthNameByMonthIndex](#getMonthNameByMonthIndex)
- [getDayOfWeekNumber](#getDayOfWeekNumber)
- [getDayOfMonthNumber](#getDayOfMonthNumber)
- [getDateByDayOfMonthNumber](#getDateByDayOfMonthNumber)
- [getNextMonth](#getNextMonth)
- [getPrevMonth](#getPrevMonth)
- [getNextDay](#getNextDay)
- [getPrevDay](#getPrevDay)
- [getFirstDateOfMonth](#getFirstDateOfMonth)
- [getLastDateOfMonth](#getLastDateOfMonth)
- [isDatesEqual](#isDatesEqual)
## Quick start
### Install
We support all platforms.
#### npm
For module bundlers such as Webpack or Browserify.
```shell
npm i date-helper-js
```
#### Include with <script>
Download and install with `script`.
```html
```
##### CDN
Recommended for learning purposes, you can use the latest version:
```html
```
Recommended for production for avoiding unexpected breakage from newer versions:
```html
```
### Initialization
#### ES6
date-helper-js as an ES6 module.
```js
import { getMonthNameByMonthIndex } from 'date-helper-js';
getMonthNameByMonthIndex(1)
```
#### Node
date-helper-js as a Node.js module
```js
const { getMonthNameByMonthIndex } = require('date-helper-js');
getMonthNameByMonthIndex(1)
```
#### Browser
Exports a global variable called `dateHelper`. Use it like this
Connect to html file ``````
```html
```
#### AMD
date-helper-js as an AMD module. Use with Require.js, System.js, and so on.
1. Download lib
2. Connect to your module loader
```js
requirejs(['date-helper'], function(dateHelper) {
dateHelper.getMonthNameByMonthIndex(1)
});
```
## Methods
### getMonthNameByMonthIndex
Return monthName by month index
#### Params
- `monthIndex`
- Type: `number`
- `arrayOfMonthNames`
- Type: `Array.<string>`
#### Returns
- `string`
#### Example
```JS
const monthIndex = 1
const monthNamesArray = ['January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September', 'October', 'November', 'December']
getMonthNameByMonthIndex(monthIndex, monthNamesArray)
// => 'February'
```
### getDayOfWeekNumber
Return day of week number for selected date
(0 - Sunday, 6 - Saturday)
#### Params
- `date`
- Type: `Date`
#### Returns
- `number`
#### Example
```JS
getDayOfWeekNumber(new Date("2017-01-26")) //Thursday
// => 4
```
### getDayOfMonthNumber
Return day of month number for selected date
#### Params
- `date`
- Type: `Date`
#### Returns
- `number`
#### Example
```JS
getDayOfMonthNumber(new Date("2017-01-26")) //Thursday
// => 26
```
### getDateByDayOfMonthNumber
Return Date by day of month number for selected date
#### Params
- `monthDate`
- Type: `Date`
- `dayOfMontNumber`
- Type: `Date`
#### Returns
- `Date`
#### Example
```JS
getDateByDayOfMonthNumber(new Date("2017-01-26"), 2)
// => new Date("2017-01-2")
```
### getNextMonth
Return next month Date of selected date
#### Params
- `date`
- Type: `Date`
- Description: start date
- `step`
- Type: `number`
- Description: how many steps forward
#### Returns
- `Date`
#### Example
```JS
getNextMonth(new Date("2017-01-26"))
// => new Date("2017-02-26")
getNextMonth(new Date("2017-01-26"), 2)
// => new Date("2017-03-26")
```
### getPrevMonth
Return prev month Date of selected date
#### Params
- `date`
- Type: `Date`
- Description: start date
- `step`
- Type: `number`
- Description: how many steps back
#### Returns
- `Date`
#### Example
```JS
getPrevMonth(new Date("2017-02-26"))
// => new Date("2017-01-26")
getPrevMonth(new Date("2017-03-26"), 2)
// => new Date("2017-01-26")
```
### getNextDay
Return next day Date of selected date
#### Params
- `date`
- Type: `Date`
- Description: start date
- `step`
- Type: `number`
- Description: how many steps forward
#### Returns
- `Date`
#### Example
```JS
getNextDay(new Date("2017-01-26"))
// => new Date("2017-02-27")
getNextDay(new Date("2017-01-26"), 2)
// => new Date("2017-03-28")
```
### getPrevDay
Return prev day Date of selected date
#### Params
- `date`
- Type: `Date`
- Description: start date
- `step`
- Type: `number`
- Description: how many steps back
#### Returns
- `Date`
#### Example
```JS
getPrevDay(new Date("2017-02-26"))
// => new Date("2017-01-25")
getPrevDay(new Date("2017-03-26"), 2)
// => new Date("2017-01-24")
```
### getFirstDateOfMonth
Return first day of month from selected date
#### Params
- `date`
- Type: `Date`
#### Returns
- `Date`
#### Example
```JS
getFirstDateOfMonth(new Date("2017-01-26"))
// => new Date("2017-01-01")
```
### getLastDateOfMonth
Return last day of month from selected date
#### Params
- `date`
- Type: `Date`
#### Returns
- `Date`
#### Example
```JS
getLastDateOfMonth(new Date("2017-01-26"))
// => new Date("2017-01-31")
```
### isDatesEqual
Return result of comparing two dates
#### Params
- `firstDate`
- Type: `Date`
- `secondDate`
- Type: `Date`
- `shouldCompareTime`
- Type: `boolean`
#### Returns
- `Date`
#### Example
```JS
isDatesEqual(new Date("2017-01-26"), new Date("2017-01-26"))
// => true
isDatesEqual(new Date("2017-01-26"), new Date("2017-01-27"))
// => false
isDatesEqual(new Date("2017-01-26 15:15:16"), new Date("2017-01-26 15:15:15"), true)
// => false
```
## Author
webster6667