Understanding SEO and Web Vitals for your NextJS site and how to improve them?Published on May 1, 2022Updated on May 1, 2022

Part 3 of the series breaking down my portfolio/blog development. In this part, we look at improving our page rank by focusing on core web vitals and SEO.

nextjsseocorewebvitalslighthouse

Prerequisites

Search Engine Optimization

Adding meta Tags

export const Layout: React.FC<Props> = ({ children }: Props) => {
    const router = useRouter();
    const url = `${domain}${router.asPath}`;
    return (
        <div className="flex w-full flex-col min-h-screen">
            <DefaultSeo
                titleTemplate="%s - Alan John"
                openGraph={{
                    type: "website",
                    locale: "en_IE",
                    url: url,
                    description:
                        "The personal website for Alan John, developer.",
                    site_name: "Alan John",
                    images: [
                        {
                            url: `${domain}/images/social_media_preview.png`,
                            width: 1200,
                            height: 628,
                            alt: "My Portfolio Preview",
                            type: "image/png",
                        },
                    ],
                }}
                canonical={url}
            />
            <Header />
            {children}
            <Footer />
        </div>
    );
};

const Home: NextPage = () => {
    return (
        <Layout>
            <NextSeo
                title="Home"
                description="2022 Portfolio"
                additionalMetaTags={[
                    {
                        property: "keywords",
                        content:
                            "Alan, John, Software Developer, Sofware Engineer, Developer, Portfolio",
                    },
                ]}
            />
            <Section className="mt-32 flex-grow">
						{/* Contents of Page */}
            </Section>
        </Layout>
    );
};

The contents of the meta tags has to studied properly to get best results. There are plenty of resources talking about great SEO strategies. The contents in the tags I have added are just for demonstration.

<meta name="viewport" content="width=device-width">
<meta charset="utf-8">
<meta property="og:type" content="website">
<meta property="og:image:alt" content="My Portfolio Preview">
<meta property="og:image:type" content="image/png">
<meta property="og:image:width" content="1200">
<meta property="og:image:height" content="628">
<meta property="og:locale" content="en_IE">
<meta property="og:site_name" content="Alan John">
<title>Home - Alan John</title>
<meta name="robots" content="index,follow">
<meta name="description" content="2022 Portfolio">
<meta property="og:title" content="Home - Alan John">
<meta property="og:description" content="2022 Portfolio">
<meta property="keywords" content="Alan, John, Software Developer, Sofware Engineer, Developer, Portfolio">
<meta property="og:url" content="https://alanjohn.dev/">
<meta property="og:image" content="https://alanjohn.dev/images/social_media_preview.png">
<link rel="canonical" href="https://alanjohn.dev/">

robots.txt and sitemap.xml

# Allow all user agents.
User-agent: *
Allow: /

Sitemap: https://www.alanjohn.dev/sitemap.xml

import { domain } from "./config";
import { BlogArticle } from "./interface";
import fs from "fs";

const sitemapxml = "public/sitemap.xml";

export const generateSiteMap = (posts: BlogArticle[]) => {
    const staticPages = fs
        .readdirSync("pages")
        .filter((staticPage) => {
            return ![
                "_app.tsx",
                "_document.tsx",
                "_error.tsx",
                "index.tsx",
            ].includes(staticPage);
        })
        .map((staticPagePath) => {
            return `${domain}/${staticPagePath.split(".")[0]}`;
        });

    staticPages.push(domain);

    const sitemap = `<?xml version="1.0" encoding="UTF-8"?>
    <urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">
      ${staticPages
          .map((url) => {
              return `
            <url>
              <loc>${url}</loc>
              <lastmod>${new Date().toISOString()}</lastmod>
              <changefreq>monthly</changefreq>
              <priority>1.0</priority>
            </url>
          `;
          })
          .join("")}
        ${posts
            .map((post) => {
                return `<url>
            <loc>${domain + "/blog/" + post.url}</loc>
            <lastmod>${post.modifiedDate}</lastmod>
            <changefreq>daily</changefreq>
            <priority>1.0</priority>
          </url>`;
            })
            .join("")}
    </urlset>
  `;

    fs.writeFileSync(sitemapxml, sitemap);
};

Social Media Preview Image

import { BlogArticle } from "@util/interface"; // Type definition for blog
import { getBlogArticle } from "@util/notion"; // Gets blog article details
import { getHTML } from "@util/template"; // Creates HTML preview based on template

import type { NextApiRequest, NextApiResponse } from "next";

export default async function handler(
    req: NextApiRequest,
    res: NextApiResponse,
) {
    const { id } = req.query;
    try {
        const article: BlogArticle = await getBlogArticle(id.toString());
        const html = getHTML(article);
        res.setHeader("Content-Type", "text/html");
        res.end(html);
    } catch (error) {
        console.error(error);
        res.status(400).json(error);
    }
}

import { getPreviewHTML } from "@util/get-html-preview";
// Gets the preview-html url which we screenshot

import chrome from "chrome-aws-lambda";
import type { NextApiRequest, NextApiResponse } from "next";
import puppeteer from "puppeteer-core";

export default async function handler(
    req: NextApiRequest,
    res: NextApiResponse,
) {
    const { id } = req.query;
    try {
        const url = getPreviewHTML(id.toString());
        const options = process.env.AWS_REGION
            ? {
                  args: chrome.args,
                  executablePath: await chrome.executablePath,
                  headless: chrome.headless,
              }
            : {
                  args: [],
                  executablePath:
                      process.platform === "win32"
                          ? "C:\\Program Files (x86)\\Google\\Chrome\\Application\\chrome.exe"
                          : process.platform === "linux"
                          ? "/usr/bin/google-chrome"
                          : "/Applications/Google Chrome.app/Contents/MacOS/Google Chrome",
              };
        const browser = await puppeteer.launch(options);
        const page = await browser.newPage();
        await page.setViewport({ width: 1200, height: 628 });
        await page.goto(url, { waitUntil: "networkidle0" });
        const file = await page.screenshot({ type: "png" });
        res.statusCode = 200;
        res.setHeader("Content-Type", `image/png`);
        res.setHeader(
            "Cache-Control",
            `public, immutable, no-transform, s-maxage=31536000, max-age=31536000`,
        );
        res.end(file);
    } catch (error) {
        console.error(error);
        res.status(400).json(error);
    }
}

JSON-LD

interface Author {
    "@type": "person";
    name: string;
    url: string;
}

export interface CustomArticleJsonLdProps extends JsonLdProps {
    type?: "Article" | "BlogPosting";
    url: string;
    title: string;
    images: ReadonlyArray<string>;
    datePublished: string;
    dateModified?: string;
    authorName: Author | Author[];
    description: string;
}

export const CustomArticleJsonLd: React.FC<CustomArticleJsonLdProps> = ({
    type = "Article",
    keyOverride,
    url,
    title,
    images,
    datePublished,
    dateModified,
    authorName,
    description,
}: CustomArticleJsonLdProps) => {
    const data = {
        datePublished,
        description,
        mainEntityOfPage: {
            "@type": "WebPage",
            "@id": url,
        },
        headline: title,
        image: images,
        dateModified: dateModified || datePublished,
        author: authorName,
    };
    return (
        <JsonLd
            type={type}
            keyOverride={keyOverride}
            {...data}
            scriptKey="article"
        />
    );
};

export default CustomArticleJsonLd;

<CustomArticleJsonLd
    type="BlogPosting"
    url={url}
    title={post.title}
    images={[socialimageurl]}
    datePublished={post.publishDate}
    dateModified={post.modifiedDate}
    authorName={{
        "@type": "person",
        name: "Alan John",
        url: "https://www.alanjohn.dev",
    }}
    description={truncated}
/>

What are web vitals?

💡 I have just summarised the core web vitals based on content found at https://web.dev/vitals/. My primary goal is to highlight how I improved my core web vitals and this is a prerequisite to that. If you want to learn more about web vitals in details, there is comprehensive content found at https://web.dev which i would strongly recommend. You can also refer NextJS learn.

• Largest Contentful Paint (LCP): measures loading performance. To provide a good user experience, LCP should occur within 2.5 seconds of when the page first starts loading.
• First Input Delay (FID): measures interactivity. To provide a good user experience, pages should have a FID of 100 milliseconds or less.
• Cumulative Layout Shift (CLS): measures visual stability. To provide a good user experience, pages should maintain a CLS of 0.1. or less.

Measuring web vitals using Lighthouse

npm i -g lighthouse

Improving web vitals

• First Contentful Paint marks the time at which the first text or image is painted.
• Speed Index shows how quickly the contents of a page are visibly populated.
• Largest Contentful Paint marks the time at which the largest text or image is painted.
• Time to interactive is the amount of time it takes for the page to become fully interactive.
• Total Blocking Time is sum of all time periods between FCP and Time to Interactive, when task length exceeded 50ms, expressed in milliseconds.
• Cumulative Layout Shift measures the movement of visible elements within the viewport.

Handling fonts

Performance issues due to animations

Dynamic loading for code splitting

💡 I had later removed highlight.js altogether for prism.js in this PR.

React-Notion-X

💡 As far as why the renderer in react-notion-x outperformed what I had implemented for the scope of the project, the biggest difference in approach was that react-notion-x used react’s useMemo and useContext hooks followed by a lot of better design choices at block level.

Conclusion