> ## Documentation Index
> Fetch the complete documentation index at: https://docs.appsignal.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Express

export const VersionRequirements = ({versions = []}) => {
  if (!Array.isArray(versions) || versions.length === 0) {
    return null;
  }
  const boundaries = {
    upper: " or lower",
    exact: "",
    lower: " or higher"
  };
  const containerStyle = {
    marginTop: "0.5rem",
    marginBottom: "1.5rem"
  };
  const lineStyle = {
    display: "block",
    margin: "0 0 0.35rem 0",
    fontSize: "0.875rem",
    lineHeight: "1.4"
  };
  const pillBaseStyle = {
    display: "inline-block",
    padding: "0.1em 0.4em",
    borderRadius: "0.25rem",
    border: "1px solid",
    fontFamily: "ui-monospace, SFMono-Regular, Menlo, monospace",
    fontSize: "0.85em",
    fontWeight: 500
  };
  const pillColors = {
    "AppSignal for Elixir": {
      background: "#f3e8ff",
      borderColor: "#e9d5ff",
      color: "#9333ea"
    },
    "AppSignal for Front-end": {
      background: "#fef9c3",
      borderColor: "#fde68a",
      color: "#ca8a04"
    },
    "AppSignal for Go": {
      background: "#ccfbf1",
      borderColor: "#99f6e4",
      color: "#0d9488"
    },
    "AppSignal for JavaScript": {
      background: "#fef9c3",
      borderColor: "#fde68a",
      color: "#ca8a04"
    },
    "AppSignal for Node.js": {
      background: "#dcfce7",
      borderColor: "#bbf7d0",
      color: "#16a34a"
    },
    "AppSignal for Python": {
      background: "#dbeafe",
      borderColor: "#bfdbfe",
      color: "#2563eb"
    },
    "AppSignal for Ruby": {
      background: "#fee2e2",
      borderColor: "#fecaca",
      color: "#dc2626"
    },
    "AppSignal for Rust": {
      background: "#ffedd5",
      borderColor: "#fed7aa",
      color: "#ea580c"
    }
  };
  const defaultPillColor = {
    background: "#f4f4f5",
    borderColor: "#e4e4e7",
    color: "#52525b"
  };
  const getPillStyle = name => ({
    ...pillBaseStyle,
    ...pillColors[name] || defaultPillColor
  });
  const getBoundText = bound => {
    return boundaries[bound] || boundaries.lower;
  };
  return <div style={containerStyle}>
      {versions.map((v, i) => <p key={`${v.name}-${v.version}-${v.bound || "lower"}-${i}`} style={lineStyle}>
          This feature requires{" "}
          <code style={getPillStyle(v.name)}>{v.name}</code> version {v.version}
          {getBoundText(v.bound)}.
        </p>)}
    </div>;
};

<VersionRequirements
  versions={[
{ name: "AppSignal for Node.js", version: "3.0.0" },
{ name: "Express", version: "4.0.0" }
]}
/>

<Note>
  Default instrumentations can be disabled via the `disableDefaultInstrumentations` config option. You can read more about how to configure this in our [Configuration Options documentation](/nodejs/3.x/configuration/options#option-disabledefaultinstrumentations).
</Note>

The AppSignal for Node.js integration for [Express](https://expressjs.com/).

## Installation

Express is instrumented automatically by the AppSignal for Node.js package. In order for errors occurring in your Express application to be forwarded to AppSignal, follow the instructions below to setup the error handler middleware.

## Error Handler

The module contains middleware to send any errors that take place in your Express application to AppSignal.

<CodeGroup>
  ```javascript Node.js theme={null}
  import { expressErrorHandler } from "@appsignal/nodejs";
  // or: const { expressErrorHandler } = require("@appsignal/nodejs");

  const app = express();

  // add this after all routes, but before any other error handlers
  app.use(expressErrorHandler());
  ```
</CodeGroup>

<Tip>
  Only exceptions with status code 500 and above will be reported to AppSignal
  automatically. To send exceptions to AppSignal with other status codes, you
  can use [custom exception
  handling](/nodejs/3.x/instrumentation/exception-handling).
</Tip>

## Features

The Express integration will send AppSignal a child span representing the execution time of each middleware, as well as a child span for the request handler.

The integration will use the request route as the name of the action. Request query parameters will be sent.

The request body will be sent if `req.body` is present (for example, when using a body parsing middleware such as `body-parser`)

The request cookies will be sent if `req.cookies` is present (for example, when using a cookie parsing middleware such as `cookie-parser`)

When using the error handler middleware, any errors raised by the request handler or any of the middlewares will be reported to AppSignal.