Elder.js Plugin: Images

Easily generate responsive images for your Elder.js site or use the underlying code as a library.

The core of this library offers much of the functionality of the well known gatsby-image plugin for Elder.js. In library mode, it will compress your images and upload them to s3 generating a manifest that is compatible with Elder.js should you wish to use this plugin and allow your users to host their images elsewhere.

demo For a demo of this plugin in action visit: nicholasreese.com and look at the header and post images.

This plugin works on several production sites but may still have rough edges. PRs are welcome.

What This Plugin Does:

Dealing with responsive images isn't easy. Often you need to compress in many different sizes, fiddle with picture formats, and figure out lazy loading and browser compatibility.

This plugin aims to simplify this and will take folder of non-responsive images and:

1. resizes them to various widths
2. saves them in webp + original format.
3. generates scales for high density displays
4. generates a low quality image placeholder (for the blur up effect)

So where you would usually have a non-responsive image of: /images/wide.jpeg

You can now use an Elder.js shortcode {{picture src='/images/wide.jpeg' /}} which will output (something like):

<picture
  ><source type="image/webp" media="(min-width: 1200px)" srcset="/images/wide-ejs-1200.webp" />
  <source type="image/webp" media="(min-width: 992px)" srcset="/images/wide-ejs-992.webp" />
  <source type="image/webp" media="(min-width: 768px)" srcset="/images/wide-ejs-768.webp" />
  <source
    type="image/webp"
    media="(min-width: 576px)"
    srcset="/images/wide-ejs-576.webp, /images/[e-mail] 2x" />
  <source
    type="image/webp"
    media="(min-width: 400px)"
    srcset="/images/wide-ejs-400.webp, /images/[e-mail] 2x" />
  <source
    type="image/webp"
    media="(min-width: 350px)"
    srcset="/images/wide-ejs-350.webp, /images/[e-mail] 2x" />
  <source type="image/webp" srcset="/images/wide-ejs-200.webp, /images/[e-mail] 2x" />
  <source media="(min-width: 1200px)" srcset="/images/wide-ejs-1200.jpeg" />
  <source media="(min-width: 992px)" srcset="/images/wide-ejs-992.jpeg" />
  <source media="(min-width: 768px)" srcset="/images/wide-ejs-768.jpeg" />
  <source media="(min-width: 576px)" srcset="/images/wide-ejs-576.jpeg, /images/[e-mail] 2x" />
  <source media="(min-width: 400px)" srcset="/images/wide-ejs-400.jpeg, /images/[e-mail] 2x" />
  <source media="(min-width: 350px)" srcset="/images/wide-ejs-350.jpeg, /images/[e-mail] 2x" />
  <source srcset="/images/wide-ejs-200.jpeg, /images/[e-mail] 2x" />
  <img
    src="data:image/jpeg;base64,/9j/2wBDABALDA4MChAODQ4SERATGCgaGBYWGDEjJR0oOjM9PDkzODdASFxOQERXRTc4UG1RV19iZ2hnPk1xeXBkeFxlZ2P/2wBDARESEhgVGC8aGi9jQjhCY2NjY2NjY2NjY2NjY2NjY2NjY2NjY2NjY2NjY2NjY2NjY2NjY2NjY2NjY2NjY2NjY2P/wgARCAAEAAoDASIAAhEBAxEB/8QAFgABAQEAAAAAAAAAAAAAAAAAAAID/8QAFQEBAQAAAAAAAAAAAAAAAAAAAAL/2gAMAwEAAhADEAAAAcZIf//EABgQAAIDAAAAAAAAAAAAAAAAAAABAhIx/9oACAEBAAEFAtlVH//EABQRAQAAAAAAAAAAAAAAAAAAAAD/2gAIAQMBAT8Bf//EABQRAQAAAAAAAAAAAAAAAAAAAAD/2gAIAQIBAT8Bf//EABYQAQEBAAAAAAAAAAAAAAAAAAACMf/aAAgBAQAGPwKWP//EABcQAQEBAQAAAAAAAAAAAAAAAAERACH/2gAIAQEAAT8hVXXtpmuf/9oADAMBAAIAAwAAABCL/8QAFBEBAAAAAAAAAAAAAAAAAAAAAP/aAAgBAwEBPxB//8QAFREBAQAAAAAAAAAAAAAAAAAAAAH/2gAIAQIBAT8Qr//EABoQAQACAwEAAAAAAAAAAAAAAAEAESExUdH/2gAIAQEAAT8QaBDoacRSUXfX2f/Z"
    class="lazy blur-up loaded"
    data-ll-status="loaded"
/></picture>

Helpers

In addition to the {{picture src='' alt='' /}} shortcode. This plugin adds the following to the helper object available in all Elder.js hooks after bootstrap:

helpers.images.src(path)

Takes a relative path of the image and returns all the srcsets and data from the ejs-image-manifest.json.

helpers.images.picture(path, {maxWidth: 2000, class:'', alt: '', ignoreCssString: false})

Takes a path and opts object and outputs the <picture> tag similar to the shortcode.

opts

• maxWidth The largest responsive image to be included.
• class a class added to the <picture>
• alt alt tag added to the <img>.
• ignoreCssString option to make the image ignore the default cssString styles.

If you need to use custom styles for a specific image instance but don't want to disable the default styles (cssString), you can set the ignoreCssString option to true. It will change the wrapper class .ejs to be .custom-ejs so that the default styles won't have an impact on this particular image instance.

helpers.images.largest(path, {maxWidth: 2000})

A small utility to find the largest file (up to the maxWidth) for a given image.

Default File Structure

The default plugin config assumes the following structure for your images:

root
| -- images
| -- | -- image files

It will automatically create:

root
| -- images
| -- | -- image files
| -- | -- ejs-image-manifest.json
| -- | -- sizes
| -- | -- | -- (resized images)

Install

Setup:

npm install --save @elderjs/plugin-images vanilla-lazyload

Add To elder.config.js:

Once installed, open your elder.config.js and configure the plugin by adding @elderjs/plugin-images to your plugin object.

plugins: {
    ...
    '@elderjs/plugin-images': {
        folders: [
            {
                src: '/images/*', // glob of where your original images are. Relative to rootDir/process.cwd() defined in your elder.config.js. Careful with **.
                // src: 'articles/**/*' is also acceptable
                output: '/images/', // where files should be put within the distDir defined in your elder.config.js.
            },
        ],
    }
    ...
}

FAQ:

• How to disable placeholder: set placeholder: false in your config.
• How to disabled padding on the .ejs class. Set cssString:false. This will disable the plugin from generating any css which gives you full control and will help keep your site from being impacted by future css changes.

Full Config:

plugins: {

  '@elderjs/plugin-images': {
    debug: false, // help with debugging
    s3: {
      AWS_ACCESS_KEY_ID: process.env.AWS_ACCESS_KEY_ID, // aws_access_key_id
      AWS_SECRET_ACCESS_KEY: process.env.AWS_SECRET_ACCESS_KEY, // aws_secret_access_key
      S3_BUCKET: process.env.S3_BUCKET, // s3 bucket name
      S3_BUCKET_URL: process.env.S3_BUCKET_URL, // the bucket url
      USE_S3_HOSTING: true, // images will be hosted on s3 instead of inserting relative url.
    },

    folders: [
      {
        src: '/images/', // where your original images are. Relative to rootDir/process.cwd() defined in your elder.config.js.
        output: '/images/', // where files should be put within the distDir defined in your elder.config.js.
      },
    ],
    widths: [1280, 992, 768, 576, 400, 350, 200], // Sizes the images will be resized to.
    fileTypes: ['webp'], // file types in addition to jpeg/png.
    imageManifest: '/images/ejs-image-manifest.json', // relative to root dir or an async function
    cacheFolder: '/images/sizes/', // relative to root dir
    scales: [1, 2], // 1x, 2x sizes
    placeholder: { // placeholder settings. See sharp.
      resize: {
        width: 10,
        fit: sharp.fit.cover,
      },
      jpeg: {
          // resize settings for the placeholder. See sharp.
        quality: 50,
        progressive: true,
        optimizeScans: true,
        chromaSubsampling: '4:2:0',
        trellisQuantisation: true,
        quantisationTable: 2,
      },
    },
    quality: 70, // quality to save the resized images in.
    cssString: ``, // if you want to overwrite the default css added
    addVanillaLazy: true, // if you want to disable the lazyload plugin and add your own.
    vanillaLazyLocation: '/static/vanillaLazy.min.js', // vanillaLazy's location relative to the root of the site. The plugin will move it to your public folder for you.
  }


}

Additional Notes For Usage

Within your project's root, you can add the following to further optimize this plugin's usage.

Adjust .gitignore to keep cache files out of repository

/images/sizes/
/images/*.json

Cleaning cache

Explicitly default cache related values to elder.config.js

imageManifest: '/images/ejs-image-manifest.json',
cacheFolder: '/images/sizes/',

and created package script to clear the cache when it feels appropriate

//src/cleanImageCache.js

const del = require('del');
const path = require('path');
const { getConfig } = require('@elderjs/elderjs');

const { rootDir, plugins } = getConfig();

console.log(' Clearing out image cache.');

if (plugins['@elderjs/plugin-images'] !== undefined) {
  const plugin = plugins['@elderjs/plugin-images'];
  if (plugin.imageManifest !== undefined) {
    del.sync(path.join(rootDir, plugin.imageManifest));
  }
  if (plugin.cacheFolder !== undefined) {
    del.sync(path.join(rootDir, plugin.cacheFolder));
  }
}

node ./src/cleanImageCache.js

Troubleshooting

If you are struggling with the plugin doing unexpected things, remove your ejs-image-manifest.json and let the plugin rebuild it from scratch. Generally this won't result in generating new images but can help clean up issues caused by an out of sync manifest.json.

Library Usage

This plugin also exports a processImages function which will generate sizes and optionally upload them to s3 just like it would work with the Elder.js plugin.

processImages

params:

• manifest: an prior manifest object or empty object.
• images: an array of image objects (defined below).
• widths: an array of widths.
• scales: an array of scales. ex: [1,2],
• s3: s3 options as defined in the plugin config above.
• debug: turns in/off debugging

images array for processImages

// images = [
// {
//     src,           // file path or buffer
//     rel,           // the relative url where the image will be found on the site. (used in the manifest) '/image/foo.jpg'
//     ext,           // extension : 'png', 'jpg', 'webp'
//   }
// ]

Library Use Case

This is useful if you let your users upload images to a dashboard and you want to store the processed image sizes in a database... but still want to use this plugin.

This was our use case at ElderGuide.com. Images are uploaded to an internal dashboard by our team the buffer can be sent directly to the processImages function which will generate a manifest and upload the resulting images to s3.

We then take the json generated by the library and toss it in the DB for longer term storage.

Then to use the imageManifest option in the Elder.js to build a compatible manifest.

This allows us to centrally host our images and still get all of the benefits of this plugin.

Below is an example imageManifest function:

plugins: {
  '@elderjs/plugin-images': {
    // rest of the config
    imageManifest: async () => {
      // you can do a db call to build the manifest.
      return {
        '/images/advice-seekers.jpg': {
          width: 200,
          height: 200,
          format: 'jpeg',
          original: '/images/advice-seekers.jpg',
          sizes: [
            ...
          ],
          placeholder:
            'data:image/jpeg;base64,/9j/2wBDABALDA4MChAODQ4SERATGCgaGBYWGDEjJR0oOjM9PDkzODdASFxOQERXRTc4UG1RV19iZ2hnPk1xeXBkeFxlZ2P/2wBDARESEhgVGC8aGi9jQjhCY2NjY2NjY2NjY2NjY2NjY2NjY2NjY2NjY2NjY2NjY2NjY2NjY2NjY2NjY2NjY2NjY2P/wgARCAAKAAoDASIAAhEBAxEB/8QAFgABAQEAAAAAAAAAAAAAAAAABAIG/8QAFAEBAAAAAAAAAAAAAAAAAAAAAP/aAAwDAQACEAMQAAABpefWf//EABoQAQABBQAAAAAAAAAAAAAAAAEAAhETFCH/2gAIAQEAAQUCK3Z5Bc12f//EABQRAQAAAAAAAAAAAAAAAAAAAAD/2gAIAQMBAT8Bf//EABQRAQAAAAAAAAAAAAAAAAAAAAD/2gAIAQIBAT8Bf//EABkQAAMAAwAAAAAAAAAAAAAAAAABMRBBgf/aAAgBAQAGPwJrUx0p/8QAGhABAQEAAwEAAAAAAAAAAAAAAREAITFhkf/aAAgBAQABPyFahWxz1DTILW57Pu//2gAMAwEAAgADAAAAEOP/xAAUEQEAAAAAAAAAAAAAAAAAAAAA/9oACAEDAQE/EH//xAAUEQEAAAAAAAAAAAAAAAAAAAAA/9oACAECAQE/EH//xAAcEAEAAwACAwAAAAAAAAAAAAABABEhMUFhobH/2gAIAQEAAT8Q7qhCGy68r7i67OQ5pvXI2v1T/9k=',
        },
      };
    },
  }
}

For production we proxy the s3 images in via a Cloudflare worker... in local development we set USE_S3_HOSTING to true allowing us to preview the images without the proxy.

This is really an advanced use case but power users should be aware it exists.

Special Thanks

Thanks to @meigo for helping make this work on Windows and many of the scripts in this readme.