@ohimg/ohimg-js

v1.1.4

Published

6 days ago

JavaScript SDK for OhImg - Open Graph Image Generator

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rjvim

ohimg-js

JavaScript/TypeScript SDK for OhImg - Open Graph Image Generator. Generate secure, signed Open Graph images for your website.

Features

🔒 Secure URL generation with HMAC signatures
🌐 Works everywhere (Node.js, Browsers, Deno, Cloudflare Workers)
📦 Zero dependencies
💪 Full TypeScript support
⚡ Async/await API

Installation

npm install ohimg-js
# or
yarn add ohimg-js
# or
pnpm add ohimg-js

Quick Start

import { OhImg } from "ohimg-js";

const ohimg = new OhImg({
  publishableKey: "omg_pub_xxxx", // Your OhImg API key
  signatureSecret: "omg_whsec_xxxx", // Your OhImg Signature secret
});

const ogImageUrl = await ohimg.getImageUrl({
  path: "/blog/my-post",
  domain: "https://myblog.com",
});

Framework Examples

Next.js

// pages/blog/[slug].tsx
import { OhImg } from "ohimg-js";

export default function BlogPost({ ogImageUrl }) {
  return (
    <Head>
      <meta property="og:image" content={ogImageUrl} />
      <meta property="twitter:image" content={ogImageUrl} />
    </Head>
  );
}

export async function getStaticProps({ params }) {
  const ohimg = new OhImg({
    publishableKey: process.env.OHIMG_API_KEY!,
    signatureSecret: process.env.OHIMG_WEBHOOK_SECRET!,
  });

  const ogImageUrl = await ohimg.getImageUrl({
    path: `/blog/${params.slug}`,
    domain: process.env.NEXT_PUBLIC_DOMAIN!,
  });

  return {
    props: { ogImageUrl },
  };
}

Astro

---
import { OhImg } from 'ohimg-js';

const ohimg = new OhImg({
  publishableKey: import.meta.env.OHIMG_API_KEY,
  signatureSecret: import.meta.env.OHIMG_WEBHOOK_SECRET
});

const ogImageUrl = await ohimg.getImageUrl({
  path: Astro.url.pathname,
  domain: import.meta.env.SITE
});
---

<meta property="og:image" content={ogImageUrl} />

API Reference

Configuration

const ohimg = new OhImg({
  publishableKey: string;        // Required: Your OhImg API key
  signatureSecret: string; // Required: Your OhImg Signature secret
  baseUrl?: string;      // Optional: Custom base URL (default: https://og.ohimg.dev)
});

Methods

getImageUrl(input)

Generate a complete OG image URL.

const url = await ohimg.getImageUrl({
  path: string;   // Required: Path of the page (e.g., '/blog/post')
  domain: string; // Required: Full domain with protocol (e.g., 'https://example.com')
});

generateSignature(input)

Generate signature components separately.

const {
  signature,  // Generated HMAC signature
  fullUrl     // Complete URL
} = await ohimg.generateSignature({
  path: string;   // Required: Path of the page
  domain: string; // Required: Full domain with protocol
});

Helper Function

For one-off usage:

import { getOGImageUrl } from "ohimg-js";

const ogImageUrl = await getOGImageUrl(
  {
    publishableKey: "omg_pub_xxxx",
    signatureSecret: "omg_whsec_xxxx",
  },
  {
    path: "/about",
    domain: "https://myblog.com",
  }
);

Environment Variables

OHIMG_API_KEY=omg_pub_xxxx
OHIMG_WEBHOOK_SECRET=omg_whsec_xxxx

Security

This SDK uses HMAC-SHA256 for request signing with these security features:

Domain validation
URL tampering prevention
Protocol enforcement

Troubleshooting

Common errors:

// Domain must include protocol
❌ domain: 'myblog.com'
✅ domain: 'https://myblog.com'

// Path must start with /
❌ path: 'blog/post'
✅ path: '/blog/post'

// API key and Signature secret required
❌ new OhImg({ publishableKey: '' })
✅ new OhImg({ publishableKey: 'omg_pub_xxx', signatureSecret: 'omg_whsec_xxx' })

License

MIT

Support

GitHub Issues: Report a bug
Twitter: @rjvim
Contact Email: [email protected]