![linqjs.png](https://cdn.steemitimages.com/DQmecCSuSwCqMYsfGHVn8Fu8LuRsrPu1EtuDMLqApMnHJa2/linqjs.png)

### Repository
[https://github.com/mihaifm/linq](https://github.com/mihaifm/linq)

### What Will I Learn?
- You will learn about linqjs.
- You will learn how to install linqjs with your project.
- You will learn how to summation values using linqjs.
- You will learn how to average values using linqjs.
- You will learn how to minimum values using linqjs.
- You will learn how to maximum values using linqjs.
- You will learn how to select specific column values using linqjs.

### Requirements
- Node.JS
- Basic knowledge of Javascript
- Any suitable code editor

### Difficulty
- Basic/Intermediate

### Tutorial Contents
#### 1. About linqjs
LINQ (Language Integrated Query) is query syntax in C# and VB.NET for saving and retrieving data from different sources. Linqjs is a javascript implementation of the .NET LINQ library. Which allows saving and retrieving data from json or array. It contains all the origial .NET methods with some extra methods.

#### 2. Install
> npm install linq

At the start of the javascript file add this line.
> const rlinq = require('linq');

This line will include linqjs package to the script so we can work with it.

### Declare an array which will be used on our following steps of tutorial
![products.png](https://cdn.steemitimages.com/DQmYvggfp3uFwhFMcJiyFbYyzRXteUgCe9tE3QmCvGhdaC7/products.png)
We have declared an array of products. which contains products id, name and its price.

> var products = [
    { "id": 100, "name": "Pendrive", "price": 500 },
    { "id": 101, "name": "Ram", "price": 1000 },
    { "id": 102, "name": "Motherboard", "price": 5000 },
    { "id": 103, "name": "Keyboard", "price": 450 }
]

#### 3. Summation 
Our target is to summation the total price of the products. Our following single line of code using linqjs will summarize the total price of products.

> var totalprice = rlinq.from(products).sum("$.price");

Explanation : 
- <b>rlinq</b> is the references of <b>linqjs</b>
- we have passed products list on the parameter of <b>from</b> function
- we mentioned <b>price</b> to sum by passing <b>$.price</b>(lambda expression) as a parameter of sum function
- this will return the summarize price of products


#### 4. Average 
Our target is to calculate the average price of the products. Our following single line of code using linqjs will return the average price of the products.

> var averageprice = rlinq.from(products).average("$.price");

Explanation : 
- <b>rlinq</b> is the references of <b>linqjs</b>
- we have passed products list on the parameter of <b>from</b> function
- we mentioned <b>price</b> to calculate average by passing <b>$.price</b>(lambda expression) as a parameter of average function
- this will return the average price of products


#### 5. Minimum
Our target is to find out minimum price of the products. Our following single line of code using linqjs will return the minimum price.

> var minimumprice = rlinq.from(products).min("$.price");

Explanation : 
- <b>rlinq</b> is the references of <b>linqjs</b>
- we have passed products list on the parameter of <b>from</b> function
- we mentioned <b>price</b> to find minimum by passing <b>$.price</b>(lambda expression) as a parameter of min function
- this will return the minimum price of products

#### 6. Maximum
Our target is to find out maximum price of the products. Our following single line of code using linqjs will return the maximum price.

> var maximumprice = rlinq.from(products).max("$.price");

Explanation : 
- <b>rlinq</b> is the references of <b>linqjs</b>
- we have passed products list on the parameter of <b>from</b> function
- we mentioned <b>price</b> to find maximum by passing <b>$.price</b>(lambda expression) as a parameter of max function
- this will return the maximum price of products

#### 7. Select
Our target is to select all products name in a array. Our following single line of code using linqjs will return all products name.

> var productName = rlinq.from(products).select("$.name").toArray();

Explanation : 
- <b>rlinq</b> is the references of <b>linqjs</b>
- we have passed products list on the parameter of <b>from</b> function
- we mentioned <b>name</b> to find maximum by passing <b>$.name</b>(lambda expression) as a parameter of select function
- toArray function will make a list of product name from original product list

### Proof of Work Done
[Tutorial Code](https://github.com/touhidalam69/linqjsTutorial/blob/master/src/01_lambda_Sum_Avarage_Minimum_Maximum_Select.js)
GitHub: [https://github.com/touhidalam69/linqjsTutorial](https://github.com/touhidalam69/linqjsTutorial)