Custom Translation in HTML Value Card

This recipe shows how to use custom translation keys inside an HTML Value Card widget. The i18n keys in the HTML template are automatically resolved to the user’s interface language.

Prerequisites

A ThingsBoard instance with custom translation configured
A device sending temperature telemetry

Add Translation Keys

Navigate to White labeling ⇾ Custom translation and add the following keys for the target language (e.g., German):

Term key	English	German	Description
`custom.devices.smart-device.name`	Smart Device	Intelligentes Gerät	Device name
`custom.my-dashboard.title`	My Dashboard	Mein Dashboard	Dashboard title
`custom.my-widget.telemetry-key.temperature`	Temperature	Temperatur	Telemetry key label
`custom.my-widget.telemetry-value.low-temperature`	Low temperature	Niedrigtemperatur	Low temperature
`custom.my-widget.telemetry-value.high-temperature`	High temperature	Hochtemperatur	High temperature
`custom.my-widget.telemetry-value.normal-temperature`	Normal temperature	Normaltemperatur	Normal temperature

Open the dashboard in edit mode and click Add widget.
Select HTML Value Card from the Cards widgets bundle.
Specify the device and temperature telemetry key as the data source.
Go to the Appearance tab and paste the following HTML into the HTML field:

<script>
    var description = document.getElementsByClassName('description')[0];
    var temperature = ${temperature};
    if(temperature>=25){
        description.innerText = "{i18n:custom.my-widget.telemetry-value.high-temperature}";
    }else if(temperature<=19){
        description.innerText  = "{i18n:custom.my-widget.telemetry-value.low-temperature}";
    }else{
        description.innerText = "{i18n:custom.my-widget.telemetry-value.normal-temperature}"
    }
</script>

<div class='card'>
    <div class='content'>
        <div class='column'>
            <h1>{i18n:custom.devices.smart-device.name}</h1>
            <div class='value'>
                {i18n:custom.my-widget.telemetry-key.temperature}: ${temperature:0} °C
            </div>
            <div class='description'>
            </div>
        </div>
    </div>
</div>