Isomorphic Next
API Reference

Headers API 🧪

API reference for the headers module

Headers API

Experimental

This is an experimental feature and may change in the future.

The headers module provides a unified way to access HTTP headers in both server and client environments.

Import

import { headers } from "isomorphic-next/headers";

Methods

headers()

Returns the headers object that provides access to all request headers.

const headersList = headers();

get(name)

Retrieves the value of a specific header.

const userAgent = headers().get("user-agent");

Parameters

  • name (string): The name of the header to retrieve

Returns

  • string | null: The header value if found, null otherwise

has(name)

Checks if a specific header exists.

const hasContentType = headers().has("content-type");

Parameters

  • name (string): The name of the header to check

Returns

  • boolean: True if the header exists, false otherwise

entries()

Returns an iterator of all header entries.

for (const [name, value] of headers().entries()) {
  console.log(`${name}: ${value}`);
}

keys()

Returns an iterator of all header names.

for (const name of headers().keys()) {
  console.log(name);
}

values()

Returns an iterator of all header values.

for (const value of headers().values()) {
  console.log(value);
}

Types

interface Headers {
  get(name: string): string | null;
  has(name: string): boolean;
  entries(): IterableIterator<[string, string]>;
  keys(): IterableIterator<string>;
  values(): IterableIterator<string>;
}

Best Practices

  1. Header names are case-insensitive
  2. Use the has() method to check for header existence before accessing
  3. Consider fallback values when headers might not be present

Examples

Basic Usage

import { headers } from "isomorphic-next/headers";
 
function MyComponent() {
  const contentType = headers().get("content-type");
  const userAgent = headers().get("user-agent");
 
  return (
    <div>
      <p>Content Type: {contentType}</p>
      <p>User Agent: {userAgent}</p>
    </div>
  );
}

Iterating Over Headers

import { headers } from "isomorphic-next/headers";
 
function logAllHeaders() {
  const headersList = headers();
  for (const [name, value] of headersList.entries()) {
    console.log(`${name}: ${value}`);
  }
}

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