> ## Documentation Index > Fetch the complete documentation index at: https://docs.neuro-tech.io/llms.txt > Use this file to discover all available pages before exploring further. # Read a sensor > Make a first read using the Agent Things JavaScript API This guide reads momentary values from one standalone device. It assumes the device already exists; creating and provisioning device firmware is a separate task. ## Before you start Obtain: ```text theme={null} Neuron host: https://neuron.example.com Account: Device JID: sensor@example.net ``` The account must be able to communicate with the device, and the device's provisioning rules must allow sensor readouts. An address alone does not grant access. ## 1. Load the client libraries Create a development page served over HTTPS: ```html theme={null}

Open the browser console and run the example.

``` For a page on another origin, the Neuron must allow that origin. Set the API host before making requests: ```javascript theme={null} AgentAPI.IO.SetHost("neuron.example.com", true); ``` ## 2. Sign in In the browser developer console: ```javascript theme={null} await AgentAPI.Account.Login("", "", 3600); ``` The library keeps the JWT in browser session storage. Do not put the password or token in the page's source. ## 3. Read momentary fields ```javascript theme={null} const result = await AgentAPI.Things.Sensor.ReadStandaloneDevice( "sensor@example.net", "en", true, // momentary false, // peak false, // status false, // computed false, // identity false, // historical [], // all allowed fields null, // from null, // to null // when ); console.log(result.Fields); console.log(result.Errors); ``` Success means `result.Fields` contains one or more values, or the device returns a valid empty readout. Preserve each field's timestamp, unit, type, and quality information. ## If the read fails * **Authentication error:** confirm the Agent API login first. * **Device unavailable:** verify the JID, roster relationship, and device connection. * **Forbidden or empty result:** review provisioning for this account and field set. * **Browser CORS error:** host the page on the Neuron or allow its exact origin. Next, learn the [device model](/iot/device-model) before addressing concentrator nodes, or see [sensor data](/iot/sensor-data) before requesting historical or subscribed values.