JavaScript is a versatile, high-level programming language primarily used for creating dynamic and interactive web content. To send data from a JavaScript app to Axiom, use one of the following libraries of the Axiom JavaScript SDK: The choice between these options depends on your individual requirements:
Capabilities@axiomhq/js@axiomhq/logging
Send data to AxiomYesYes
Query dataYesNo
Capture errorsYesNo
Create annotationsYesNo
TransportsNoYes
Structured logging by defaultNoYes
Send data to multiple places from a single functionNoYes
The @axiomhq/logging library is a logging solution that also serves as the base for other libraries like @axiomhq/react and @axiomhq/nextjs.
The @axiomhq/js and the @axiomhq/logging libraries are part of the Axiom JavaScript SDK, an open-source project and welcomes your contributions. For more information, see the GitHub repository.

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Prerequisites

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Use @axiomhq/js

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Install @axiomhq/js

In your terminal, go to the root folder of your JavaScript app and run the following command: 
npm install @axiomhq/js

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Configure environment variables

Configure the environment variables in one of the following ways:
  • Export the API token as AXIOM_TOKEN.
  • Pass the API token to the constructor of the client: 
    import { Axiom } from '@axiomhq/js';

const axiom = new Axiom({
  token: process.env.AXIOM_TOKEN,
});
  • Install the Axiom CLI, and then run the following command: 
    eval $(axiom config export -f)

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Send data to Axiom

The following example sends data to Axiom: 
axiom.ingest('DATASET_NAME', [{ foo: 'bar' }]);
await axiom.flush();
Replace DATASET_NAME with the name of the Axiom dataset where you send your data.
The client automatically batches events in the background. In most cases, call flush() only before your application exits.

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Query data

The following example queries data from Axiom: 
const res = await axiom.query(`['DATASET_NAME'] | where foo == 'bar' | limit 100`);
console.log(res);
Replace DATASET_NAME with the name of the Axiom dataset where you send your data.
For more examples, see the examples in GitHub.

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Capture errors

To capture errors, pass a method onError to the client: 
let client = new Axiom({
  token: '',
  ...,
  onError: (err) => {
    console.error('ERROR:', err);
  }
});
By default, onError is set to console.error.

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Create annotations

The following example creates an annotation: 
import { annotations } from '@axiomhq/js';

const client = new annotations.Service({ token: process.env.AXIOM_TOKEN });

await annotations.create({
  type: 'deployment',
  datasets: ['DATASET_NAME'],
  title: 'New deployment',
  description: 'Deployed version 1.0.0',
})

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Use @axiomhq/logging

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Install @axiomhq/logging

In your terminal, go to the root folder of your JavaScript app and run the following command: 
npm install @axiomhq/logging

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Send data to Axiom

The following example sends data to Axiom: 
import { Logger, AxiomJSTransport, ConsoleTransport } from "@axiomhq/logging";
import { Axiom } from "@axiomhq/js";

const axiom = new Axiom({
  token: process.env.AXIOM_TOKEN,
});

const logger = new Logger(
  {
    transports: [
      new AxiomJSTransport({ 
        axiom,
        dataset: process.env.AXIOM_DATASET,
      }),
      new ConsoleTransport(),
    ],
  }
);

logger.info("Hello, world!");

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Transports

The @axiomhq/logging library includes the following transports:
  • ConsoleTransport: Logs to the console. 
    import { ConsoleTransport } from "@axiomhq/logging";

const transport = new ConsoleTransport({
  logLevel: "warn",
  prettyPrint: true,
});
  • AxiomJSTransport: Sends logs to Axiom using the @axiomhq/js library. 
    import { Axiom } from "@axiomhq/js";
import { AxiomJSTransport } from "@axiomhq/logging";

const axiom = new Axiom({
  token: process.env.AXIOM_TOKEN,
});

const transport = new AxiomJSTransport({
  axiom,
  dataset: process.env.AXIOM_DATASET,
  logLevel: "warn",
});
  • ProxyTransport: Sends logs the proxy server function that acts as a proxy between your application and Axiom. It’s particularly useful when your application runs on top of a server-enabled framework like Next.js or Remix. 
    import { ProxyTransport } from "@axiomhq/logging";

const transport = new ProxyTransport({
  url: "/proxy",
  logLevel: "warn",
  autoFlush: { durationMs: 1000 },
});
Alternatively, create your own transports by implementing the Transport interface: 
import { Transport } from "@axiomhq/logging";

class MyTransport implements Transport {
  log(log: Transport['log']) {
    console.log(log);
  }

  flush() {
    console.log("Flushing logs");
  }
}

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Logging levels

The @axiomhq/logging library includes the following logging levels:
  • debug: Debug-level logs.
  • info: Informational logs.
  • warn: Warning logs.
  • error: Error logs.

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Formatters

Formatters are used to change the content of a log before sending it to a transport. For example: 
import { Logger, LogEvent } from "@axiomhq/logging";

const myCustomFormatter = (event: LogEvent) => {
  const upperCaseKeys = {
    ...event,
    fields: Object.fromEntries(
      Object.entries(event.fields).map(([key, value]) => [key.toUpperCase(), value])
    ),
  };

  return upperCaseKeys;
};

const logger = new Logger({
  formatters: [myCustomFormatter],
});

logger.info("Hello, world!");

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Send data from JavaScript libraries and frameworks

To send data to Axiom from JavaScript libraries and frameworks, see the following:

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Send data from Node.js

While the Axiom JavaScript SDK works on both the backend and the browsers, Axiom provides transports for some of the popular loggers: