JavaScript SEO: How it Works

Every Web Development must have knowledge of JavaScript. Traditionally, JavaScript was used to progressively enhance the site on top of its primary content. The reason why JavaScript for SEO purposes is to make sure that Googlebot sees all the content on the page, including the parts that are being dynamically added using JavaScript

What is JavaScript SEO?

JavaScript SEO is a type of technical SEO (search engine optimization) that aims to make JavaScript-heavy websites easier to crawl, index, and find. The goal is for these websites to be discovered and to appear higher in search engine results. It is largely concerned with the following:

  • Optimizing JavaScript-injected content for search engine crawling, rendering, and indexing.
  • Preventing, diagnosing, and troubleshooting ranking difficulties for websites and Single Page Applications (SPAs) created with JavaScript frameworks like React, Angular, and Vue.
  • Using best linking techniques, ensure that web pages are discoverable by search engines.

Streamlining the User Experience by improving page load speeds for pages that parse and execute JS code (UX).

Benefit Javacript for SEO

SEO purposes as you want to make sure that Googlebot sees all the content on the page, including the parts that are being dynamically added using JavaScript.

JavaScript for Page Speed

Page load times can be influenced by Javascript, which is an official ranking factor in Google’s mobile-first index. This indicates that a sluggish page may harm search rankings. What can we do to assist developers in avoiding this?

  • JavaScript Minimization
  • Non-essential JS is deferred until after the main content is presented in the DOM.
  • Incorporating crucial JS
  • JavaScript should serve JS in reduced payloads.

Problems with SEO: Even search engines have a bad user experience when a website is slow. Because Google defers loading JavaScript to save resources, it’s critical to ensure that any content served to clients is properly coded and delivered to protect rankings.

JavaScript for Metadata

It’s also worth noting that SPAs that use a router package like react-router or vue-router must take extra precautions to manage things like modifying meta tags when switching between router views. A Node.js package like vue-meta or react-meta-tags is frequently used for this.

What are the different types of router views? In five phases, here’s how linking to distinct “pages” with a Single Page Application works in React:

  • A GET request for the./index.html file is sent to the server when a user visits a React website.
  • The server then delivers the client the index.html page, including the JavaScript for launching React and React Router.
  • On the client-side, the web application is then loaded.
  • A request for the new URL is sent to the server when a user clicks on a link to proceed to a new page (/example).

Before the request reaches the server, React Router intercepts it and handles the page update. This is accomplished by changing the URL client-side and updating the displayed React components locally.

In other words, when people or bots visit a React website and click on links to URLs, they are not served several static HTML files. Instead, the React components (such as headers, footers, and body text) that are housed on the root./index.html page are restructured to display alternate content. It’s for this reason that they’re referred to as single-page applications.

How Google Handle JavaScript?


Process bot or spider bot visit the website, take content, and index it so that the website can be found on Search Engines. It starts with our crawler visiting the web page as any other browser would do. It then passes the content it sees onto the indexing stage. That is where the content is parsed and stored in our index. When links are detected, they are passed back to the crawler, and the cycle continues.


Every page goes to the renderer now. One of the biggest concerns from many SEOs with JavaScript and two-stage indexing (HTML then rendered page) is that pages might not get rendered for days or even weeks. When Google looked into this, they found pages went to the renderer at a median time of 5 seconds, and the 90th percentile was minutes. So the amount of time between getting the HTML and rendering the pages should not be a concern in most cases.


The index is a database used by search engines. The index contains information on all websites that can be found by search engines. In other words, Google crawls and indexes content in two waves: The first wave of indexing, or the instant crawling of the static HTML sent by the webserver. The second wave of indexing, or the deferred crawling of any additional content rendered via JavaScript

Make JavaScript Site SEO-friendly

Although many of the methods are familiar to SEOs, there may be minor changes.

Search engine optimization (SEO) on page

All of the standard on-page SEO standards for content, title tags, meta descriptions, alt attributes, and meta robot tags remain in effect. See On-Page SEO: A Step-by-Step Guide for further information.

When working with JavaScript websites, I frequently see the following issues: names and descriptions are frequently reused, and alt attributes on images are rarely set.

SEO “plugin” type options

These are typically referred to as modules in JavaScript frameworks. By searching for the framework + module name, such as “React Helmet,” you can find versions for many popular frameworks, including React, Vue, and Angular. Meta tags, Helmet, and Head, are all popular modules with comparable features that let you configure many of the common SEO tags.

Error pages

Because JavaScript frameworks are client-side, they can’t really throw 404 errors. When it comes to error pages, you have a few choices:

1. Use a JavaScript redirect to a page with a 404 status code.

2. Add a no-index tag and an error message like “404 Page Not Found” to the page that isn’t working. Because the actual status code received is a 200 acceptable, this will be considered a soft 404.


Routers that map to clean URLs are commonly found in JavaScript frameworks. These routers normally have a separate module that can generate sitemaps as well. Search for your system + router sitemap, for example, “Vue router sitemap.” Sitemap features may be available in many rendering solutions. Simply Google the system you’re using + sitemap, such as “Gatsby sitemap,” and you’ll almost certainly discover a pre-existing solution.


SEOs are familiar with server-side redirection like 301/302. Javascript, on the other hand, is usually executed on the client. This isn’t a problem because Google processes the page in the order in which it appears after the redirect. All signals, including PageRank, continue to transit via redirection. Search the code for “window.location.href” to locate this redirection.


For different frameworks, there are usually a few module options that allow some internationalization features, such as hreflang. They’ve typically been ported to other platforms and include i18n, intl, or, in many cases, the same modules used for header tags, such as Helmet, can be used to add needed tags.

Lazy Loading

Lazy loading is commonly dealt with using modules. If you haven’t already noticed, there are modules for almost everything you need to do while dealing with JavaScript frameworks. The most common modules for lazy loading are Lazy and Suspense. Lazy loading photos is recommended. However, content should not be lazy-loaded. This can be accomplished using JavaScript, but search engines may not recognize it correctly. More Here




Sagara is one of the leading software house based in Jakarta. We do digital product development, digital marketing, and workshops. Visit

Love podcasts or audiobooks? Learn on the go with our new app.

Recommended from Medium

Expo SDK 42 beta is now available

Why choose AngularJS for web development?

Android Native-React Native (cross-language Communication )

How to Create & Use Components in Laravel 8

Web Audio Series, Part 1: Working with the Web Audio API: Debugging Tips

Node.Js tutorial: URL-based requests on MacOs

Encodable in body of API Request

Coding Terms | COMMENTS

Get the Medium app

A button that says 'Download on the App Store', and if clicked it will lead you to the iOS App store
A button that says 'Get it on, Google Play', and if clicked it will lead you to the Google Play store
Sagara Technology Idea Lab

Sagara Technology Idea Lab

Sagara is one of the leading software house based in Jakarta. We do digital product development, digital marketing, and workshops. Visit

More from Medium

How to create multilingual support in ReactJs (i18next)

image to introduce into the react and i18next tutorial

Hacking Wordle To Justify My CS Degree

Personal Pinterest with Uploadcare Chrome Extension

5 important tips, to become a (Frontend) Software-Engineer