> For the complete documentation index, see [llms.txt](https://iot.datalit.de/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://iot.datalit.de/2-internet-of-things/iot-in-our-apps/program-the-devices/sensors/humidity-sensor.md).

# Humidity Sensor

## Goals

{% hint style="success" %}

* You know how to get a handle on the humidity sensor connected to your computer
* You can get the sensor's values, get frequently notified about new values, and distinguish between humidity and temperature values
  {% endhint %}

## Get the humidity sensor and subscribe to updates

Working with a [Humidity 2.0](https://www.tinkerforge.com/en/doc/Hardware/Bricklets/Humidity_V2.html#humidity-v2-bricklet) sensor works as described in the general article on [how to use sensors](/2-internet-of-things/iot-in-our-apps/program-the-devices/sensors.md). In this article, we assume you have successfully initialized the devices with the [Tinkerforge Device Manager](/2-internet-of-things/iot-in-our-apps/connect-to-devices/the-tinkerforge-device-manager.md), and you stored all connected devices on a global variable `devices`. We also declared a global variable called `humiditySensor`. 

Next, we need to know the device identifier, which **283**:

```javascript
// Get the humidity sensor via its device identifer
humiditySensor = devices.getDeviceByIdentifier(283);
```

Once we have a reference to the sensor, we can register a callback function:

```javascript
// We want to be informed when a new sensor value arrives
humiditySensor.registerListener(humidityChanged);
```

Of course, we have to actually define the function:

```javascript
function humidityChanged(val) {
   // Do something with the value object
}
```

## Distinguish between temperature and humidity

Since the sensor delivers two different value types, temperature and humidity, why not use the callback function to illustrate how we can distinguish both types:

```javascript
function humidityChanged(val) {
    // Get the value
    var value = val.getValue():
    
    if(value.type == "temperature") {
        // Do something
    }
    else if (value.type == "humidity") {
        // Do something else
    }
}
```

That is basically it - we can't do anything else with a [Humidity 2.0](https://www.tinkerforge.com/en/doc/Hardware/Bricklets/Humidity_V2.html#humidity-v2-bricklet) sensor.