Javascript SEO: How to optimize a Javascript website to be SEO friendly.

Javascript SEO guide.

JavaScript SEO refers to the practice of optimizing websites that heavily rely on JavaScript for search engine indexing and ranking. Traditional search engine crawlers like Googlebot and Bing were primarily designed to index and analyze HTML content. However, with the rise of dynamic web applications using JavaScript frameworks like React, Angular, and Vue.js, SEO practitioners faced new challenges.

Key Considerations and Examples for JavaScript SEO:

1. Renderability:

Example Code:

document.addEventListener('DOMContentLoaded', function() {
    // Your JavaScript logic here
  1. Server-Side Rendering (SSR):

Example Code (Next.js):

    import React from 'react';

    const MyPage = ({ data }) => (
            {/* Your component JSX */}

    export async function getServerSideProps() {
        // Fetch data on the server
        const data = await fetchData();

        return {
            props: {

    export default MyPage;
  1. Pre-rendering:

Example Code:

    # Install
    npm install -g

    # Run to pre-render your pages
    prerender --folder ./path/to/your/static/site
  1. Dynamic Rendering:

    • Dynamic rendering changes how content is given based on the user's device. For search engines, they get a fully made version, while users with JavaScript get a dynamic version. This is often done by checking the user's device on the server, ensuring good SEO without hurting user experience.

Example Code:

    // Express.js middleware for dynamic rendering
    app.use((req, res, next) => {
        const userAgent = req.headers['user-agent'];

        if (/bot|googlebot|crawler|spider|robot/i.test(userAgent)) {
            // Serve fully rendered version for bots
            // Your server-side rendering logic here
        } else {
            // Serve client-rendered version for regular users
            // Your client-side rendering logic here

  1. Progressive Enhancement:

Example Code:

    <!-- Basic HTML structure without JavaScript -->
    <!DOCTYPE html>
    <html lang="en">
        <meta charset="UTF-8">
        <meta name="viewport" content="width=device-width, initial-scale=1.0">
        <title>My Website</title>
        <h1>Welcome to My Website</h1>
        <!-- Your non-JavaScript content here -->

    <!-- JavaScript enhancement -->
        document.addEventListener('DOMContentLoaded', function() {
            // Your JavaScript enhancements here
  1. Structured Data:

Example Code:

    <!-- Example markup for an article -->
    <script type="application/ld+json">
        "@context": "",
        "@type": "Article",
        "headline": "Article Title",
        "datePublished": "2023-11-24",
        // Additional properties
  1. Canonicalization:

    • [Use canonical tags to tell search engines which version of a page you prefer]( when dealing with similar content. This is crucial for JavaScript sites with multiple URLs leading to similar content, helping search engines understand and index your pages accurately.

Example Code:

    <!-- Canonical tag to specify the preferred version -->
    <link rel="canonical" href="">
  1. JavaScript Framework Best Practices:

Example Code (React):

    // Example React component with proper SEO practices
    import React from 'react';

    const MyComponent = () => (
            <h1>My Component</h1>
            {/* Your component JSX */}

    export default MyComponent;
  1. Lazy Loading:

    • Use lazy loading for images and other media elements to speed up page loading. By loading these elements only when they are about to be seen, you reduce the time it takes for your page to load, which is good for both user experience and SEO.

Example Code:

    <!-- Image with lazy loading attribute -->
    <img src="placeholder.jpg" data-src="actual-image.jpg" loading="lazy" alt="Description">
  1. Monitor and Test:

Example Code:

    // Example A/B testing implementation
    const experimentVariant = Math.random() < 0.5 ? 'variantA' : 'variantB';

    // Implement logic based on the selected variant
    if (experimentVariant === 'variantA') {
        // Your variant A logic
    } else {
        // Your variant B logic

To conclude: JavaScript SEO is always changing and requires a careful approach. By dealing with technical details, using best practices, and staying updated on changes in search engines and JavaScript frameworks, you can build a strong SEO strategy for JavaScript-based websites. This will ultimately improve how well your site shows up and ranks in search engine results."