# How to install Node.js library on Linux

{% hint style="warning" %}
This documentation is for the LEGACY version of Blynk platform which is no longer supported and will be shut down. 

You can sign up for the current version of Blynk platform [here](http://blynk.cloud/dashboard/register).

The new mobile apps can be downloaded from [App Store](https://apps.apple.com/us/app/blynk-iot/id1559317868) and [Google Play](https://play.google.com/store/apps/details?id=cloud.blynk\&hl=en\&gl=US).

The actual Blynk documentation is [here](https://docs.blynk.io/).
{% endhint %}

First of all, you need to install Node.js.

Before updating Node.js, please be sure to remove old versions:

```
sudo apt-get purge node nodejs node.js -y
sudo apt-get autoremove
```

### Automatic Node.js installation <a href="#automatic-nodejs-installation" id="automatic-nodejs-installation"></a>

Add repositories:

```
curl -sL https://deb.nodesource.com/setup_6.x | sudo -E bash -
```

Install Node.js:

```
sudo apt-get update && sudo apt-get upgrade
sudo apt-get install build-essential nodejs -y
```

### Manual Node.js installation <a href="#manual-nodejs-installation" id="manual-nodejs-installation"></a>

Automatic install might not work for you, in this case you can perform manual installation.\
If `uname -m` gives you **armv6l** (on Raspberry Pi, usually), try this:

```
sudo su

cd /opt

wget https://nodejs.org/dist/v6.9.5/node-v6.9.5-linux-armv6l.tar.gz -O - | tar -xz
mv node-v6.9.5-linux-armv6l nodejs

apt-get update && apt-get upgrade
apt-get install build-essential

ln -s /opt/nodejs/bin/node /usr/bin/node
ln -s /opt/nodejs/bin/node /usr/bin/nodejs
ln -s /opt/nodejs/bin/npm /usr/bin/npm

exit

export PATH=$PATH:/opt/nodejs/bin/
```

### Check your Node.js and npm installation <a href="#check-your-nodejs-and-npm-installation" id="check-your-nodejs-and-npm-installation"></a>

```
pi@raspberrypi:/ $ node --version
v6.9.5

pi@raspberrypi:/ $ npm -v
3.10.10
```

### Install Blynk globally <a href="#install-blynk-globally" id="install-blynk-globally"></a>

```
sudo npm install blynk-library -g
sudo npm install onoff -g
```

Run default Blynk client (replace `YourAuthToken`):

```
export PATH=$PATH:/opt/nodejs/bin/
unset NODE_PATH
blynk-client YourAuthToken
```

### Creating a new Node.js project with Blynk <a href="#creating-a-new-nodejs-project-with-blynk" id="creating-a-new-nodejs-project-with-blynk"></a>

Installing Blynk globally may not work or can be undesired.\
In this case, you need to create a new Node.js module with local Blynk library dependency.

```
mkdir my-awesome-project
cd my-awesome-project
npm init
```

It will prompt you for general information about your project and create a `package.json` file (project description). Next, add Blynk to your project:&#x20;

```
npm install blynk-library --save
```

You can also install onoff, if you want (allows direct pin operations):

```
npm install onoff --save
```

Now create your main script file `index.js` (just replace `YourAuthToken`):

```
var Blynk = require('blynk-library');

var AUTH = 'YourAuthToken';

var blynk = new Blynk.Blynk(AUTH);

var v1 = new blynk.VirtualPin(1);
var v9 = new blynk.VirtualPin(9);

v1.on('write', function(param) {
  console.log('V1:', param[0]);
});

v9.on('read', function() {
  v9.write(new Date().getSeconds());
});
```

&#x20;This is it. Run your project:

```
node index.js
```

You should see something like:

```
OnOff mode
Connecting to: blynk-cloud.com 8441
SSL authorization...
Connected
Authorized
```

Write our own script based on [examples](https://github.com/vshymanskyy/blynk-library-js/tree/master/examples)!<br>

### What next? <a href="#what-next" id="what-next"></a>

Read about [**Virtual Pins**](http://help.blynk.cc/blynk-basics/what-is-virtual-pins) concept and unleash full power of Blynk.\
Blynk supports huge amount of board types. [Check if your favourite is on the list!](https://github.com/blynkkk/blynkkk.github.io/blob/master/SupportedHardware.md)\
Our library is Open Source Software. [Give](https://github.com/blynkkk/blynk-library/blob/master/README.md) us a star on GitHub.<br>

### Troubleshooting <a href="#troubleshooting" id="troubleshooting"></a>

If you are trying to connect to Blynk cloud, and get an error like:

```
npm ERR! Error: SSL Error: CERT_NOT_YET_VALID
```

you should use the `date` command to update current system time.<br>

### Further reading <a href="#further-reading" id="further-reading"></a>

[Instructables: Use DHT11/DHT12 sensors with Raspberry Pi and Blynk](http://www.instructables.com/id/Raspberry-Pi-Nodejs-Blynk-App-DHT11DHT22AM2302/?ALLSTEPS)\
[Node.js vs C++ library](http://help.blynk.cc/hardware-and-libraries/nodejs-vs-c-library)<br>