🎉 Nuxt Prune HTML

Nuxt module to prune html before sending it to the browser (it removes elements matching CSS selector(s)), useful for boosting performance showing a different HTML for bots by removing all the scripts with dynamic rendering.

💘 Motivation

Due to the versatility of Nuxt (and of the SSR in general), a website generated (or served) via node, has everything it needs already injected (in the HTML, ex. styles). So, usually, for a bot or for a human, the website its almost visually the same without Javascript.

These library was born to remove the scripts injected in the HTML only if a visitor is a Bot or a "Chrome Lighthouse". This should speed up (blazing fast) your nuxt-website up to a value of ~95 in performance during an Audit because it cheats various scenarios.

This could cause some unexpected behaviors.

Pro et contra

N.B. : Valid for Bots, PageSpeed Insights, Google Measure and Lighthouse Audits. This is known as Dynamic Rendering

Cons:

• no SPA navigation;
• no lazy-load for images (available only if native, or with a custom script / selectorToKeep, check the configuration);
• no <client-only> html.

Pro:

• some of these features aren't "used by" a Bot or a Lighthouse Audit, so you don't really need them (ex. Bots doesn't need SPA navigation, client-only tags could lead in a slower TTI); -lazy-load can be restored with a custom script / selectorToKeep, only for matched Bots;
• less HTML;
• Bots only have the Javascript they need;
• is not considered black-hat or cloaking;
• PageSpeed Insights, Measure and Lighthouse Audit in Chrome are already triggered by the plugin without the needing of change any value;
• fast TTI, fast FCP, fast FMP, fast all.

Inspired by this rcfs and this issue.

Advices

• Before setting up the module, try to Disable JavaScript With Chrome DevTools while navigate your website, this is how your website appear to a Bot (with this module activated);
• If you generate your site it's not possibile to check the user-agent, so i choose to always prune HTML (you can disable this behavior by setting the hookGeneratePage configuration value to false);
• If you use some <client-only> components, you should prepare a version that is visually the same with the placeholder slot;
• This plugin was thought for Bots and uses only the remove() method of Cheerio;
• You can check the website as a GoogleBot, following this guide.

Related things you should know

• It use the MobileDetect library to check if .is( 'bot' ), .match( options.lighthouseUserAgent ) or .match( options.matchUserAgent );
• Nuxt hooks, so the plugin has access to req.headers[ 'user-agent' ] only if the project is running as a server (ex. nuxt start);
• It use Cheerio, jQuery for servers, library to prune the html.

💡 Lighthouse

Setup

1. Add @luxdamore/nuxt-prune-html dependency to your project;
2. Add @luxdamore/nuxt-prune-html in the modules section of your nuxt.config.js;

    yarn add @luxdamore/nuxt-prune-html # or npm install --save @luxdamore/nuxt-prune-html

Configuration

N.B. : the config is only shallow merged, not deep merged.

    // nuxt.config.js
    export default {

        // Module installation
        modules: [ '@luxdamore/nuxt-prune-html' ],

        // Module config
        pruneHtml: {
            hideErrorsInConsole: false,
            hideGenericMessagesInConsole: false, // Disabled in production
            enabled: false, // Disabled in dev-mode due to the hot reload (is client-side)
            selectors: [ // Css selectors to prune
                'link[rel="preload"][as="script"]',
                'script:not([type="application/ld+json"])',
            ],
            selectorToKeep: null, // Disallow pruning of scripts with this class, N.B.: this selector will be appended to every selectors, `ex. script:not([type="application/ld+json"]):not(__VALUE__)`
            script: [], // Inject custom scripts only for matched UA (BOTS-only)
            link: [], // Inject custom links only for matched UA (BOTS-only)
            cheerio: { // It use Cheerio under the hood, so this is the config passed in the cheerio.load() method
                xmlMode: false,
            },
            ignoreBotOrLighthouse: false, // Remove selectors in any case, not depending on Bot or Lighthouse
            isBot: true, // Remove selectors if is a bot
            isLighthouse: true, // Remove selectors if match the Lighthouse UserAgent
            matchUserAgent: null, // Remove selectors if this userAgent is matched, either as String or RegExp (a string will be converted to a case-insensitive RegExp in the MobileDetect library)
            hookRenderRoute: true, // Activate the prune during the `hook:render:route`
            hookGeneratePage: true, // Activate the prune during the `hook:generate:page`
            lighthouseUserAgent: 'lighthouse', // Value of the Lighthouse UserAgent, either as String or RegExp (a string will be converted to a case-insensitive RegExp in the MobileDetect library)
            headerName: 'user-agent', // Value of a custom header name passed from a Lambda Edge function, or similar
        },

    };

With link and script it's possibile to add one or more objects ex.:

    export default {
        pruneHtml: {
            script: [
                {
                    src: '/my-custom-lazy-load-for-bots.js',
                    lazy: true,
                    defer: true,
                },
            ],
            link: [
                {
                    src: '/my-custom-lazy-load-for-bots.js',
                    rel: 'preload',
                    as: 'script',
                    position: 'phead', // Default value is 'body' --> Other allowed values are: 'phead', 'head' and 'pbody'
                },
            ],
        },
    };

Development

1. Clone this repository;
2. Install dependencies using yarn install or npm install;
3. Start development server using yarn dev or npm run dev;
4. Build Github Pages using yarn generate or npm run generate (the content is automatically generated into the /docs folder).

🐞 Issues

Please make sure to read the Issue Reporting Checklist before opening an issue. Issues not conforming to the guidelines may be closed immediately.

👥 Contribution

Please make sure to read the Contributing Guide before making a pull request.

📖 Changelog

Details changes for each release are documented in the release notes.

📃 License

MIT License // Copyright (©) 2019-present Luca Iaconelli

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