#Use @axiomhq/js

#Install @axiomhq/js

In your terminal, go to the root folder of your JavaScript app and run the following command:

```shell
npm install @axiomhq/js
```

#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)

#Send data to Axiom

The following example sends data to Axiom:

axiom.ingest('DATASET_NAME', [{ foo: 'bar' }]);
await axiom.flush();

The client automatically batches events in the background. In most cases, call flush() only before your application exits.

#Query data

The following example queries data from Axiom:

const res = await axiom.query(`['DATASET_NAME'] | where foo == 'bar' | limit 100`);
console.log(res);

For more examples, see the examples in GitHub.

#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.

#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',
})

#Use @axiomhq/logging

#Install @axiomhq/logging

In your terminal, go to the root folder of your JavaScript app and run the following command:

npm install @axiomhq/logging

#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!");

#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");
  }
}

#Logging levels

The @axiomhq/logging library includes the following logging levels:

• debug: Debug-level logs.
• info: Informational logs.
• warn: Warning logs.
• error: Error logs.

#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!");

#Related logging options

#Send data from JavaScript libraries and frameworks

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

• Send data from React app
• Send data from Next.js app

#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:

• Pino
• Winston