Image

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Using Eleventy’s official image plugin

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Low level utility to perform build-time image transformations for both vector and raster images. Output multiple sizes, save multiple formats, cache remote images locally. Uses the sharp image processor.

You maintain full control of your HTML—this plugin does not generate any markup. Use with <picture> or <img> or CSS background-image, or others! Works great to add width and height to your images! Does not require or rely on file extensions (like .png or .jpg) in URLs or local files, which may be missing or inaccurate.

• Accepts: jpeg, png, webp, gif, tiff, avif New in Image 0.6.0, and svg.
• Output multiple sizes, keeps original aspect ratio. Never upscales raster images larger than original size (unless using SVG input).
• Output multiple formats, supports: jpeg, png, webp, avif New in Image 0.6.0, and svg (requires SVG input)
• Retrieve metadata about your new images (see sample return object).
  • Use this to add width and height attributes on <img> elements for proper aspect ratio mapping.
• Save remote images locally using eleventy-cache-assets.
  • Use local images in your HTML to prevent broken image URLs.
  • Manage the cache duration.
• De-duplicates and caches repeat calls using the same source image and the same output options. New in Image 0.7.0
• Manage plugin concurrency.
• eleventy-img on GitHub

Installation #

• eleventy-img on npm

npm install --save-dev @11ty/eleventy-img

Usage #

This utility returns a Promise and works best in async friendly functions, filters, shortcodes. It can also work in synchronous environments (Synchronous Usage).

const Image = require("@11ty/eleventy-img");

(async () => {
  let url = "https://images.unsplash.com/photo-1608178398319-48f814d0750c";
  let stats = await Image(url, {
    widths: [300]
  });

  console.log( stats );
})();

Three things happen here:

1. If the first argument is a full URL (not a local file path), we download the remote image and cache it locally using the Cache plugin. This cached original is then used for the cache duration to avoid a bunch of network requests.
2. From that cached full-size original, images are created for each format and width, in this case: ./img/6dfd7ac6-300.webp and ./img/6dfd7ac6-300.jpeg.
3. The metadata object is populated and returned, describing those new images:

{
  webp: [
    {
      format: 'webp',
      width: 300,
      height: 300,
      filename: '6dfd7ac6-300.webp',
      outputPath: 'img/6dfd7ac6-300.webp',
      url: '/img/6dfd7ac6-300.webp',
      sourceType: 'image/webp',
      srcset: '/img/6dfd7ac6-300.webp 300w',
      size: 10184
    }
  ],
  jpeg: [
    {
      format: 'jpeg',
      width: 300,
      height: 300,
      filename: '6dfd7ac6-300.jpeg',
      outputPath: 'img/6dfd7ac6-300.jpeg',
      url: '/img/6dfd7ac6-300.jpeg',
      sourceType: 'image/jpeg',
      srcset: '/img/6dfd7ac6-300.jpeg 300w',
      size: 15616
    }
  ]
}

Here’s the output images, one webp and one jpeg:

Output Widths #

Controls how many output images will be created for each image format. Aspect ratio is preserved.

• widths: [null] (default, keep original width)
• widths: [200] (output one 200px width)
• widths: [200, null] (output 200px and original width)

Output Formats #

Use almost any combination of these:

• formats: ["webp", "jpeg"] (default)
• formats: ["png"]
• formats: [null] (keep original format) New in Image 0.4.0
• formats: ["svg"] (requires SVG input) New in Image 0.4.0
• formats: ["avif"] New in Image 0.6.0

URL Path #

A path-prefix-esque directory for the <img src> attribute. e.g. /img/ for <img src="/img/MY_IMAGE.jpeg">:

• urlPath: "/img/" (default)

Output Directory #

Where to write the new images to disk. Project-relative path to the output image directory. Maybe you want to write these to your output directory directly (e.g. ./_site/img/)?

• outputDir: "./img/" (default)

Caching Remote Images Locally New in Image 0.3.0 #

For any full URL first argument to this plugin, the full-size remote image will be downloaded and cached locally. See all relevant eleventy-cache-assets options.

{
  cacheOptions: {
    // if a remote image URL, this is the amount of time before it fetches a fresh copy
    duration: "1d",

    // project-relative path to the cache directory
    directory: ".cache",

    removeUrlQueryParams: false,
  },
}

Skip raster formats for SVG New in Image 0.4.0 #

If using SVG output (the input format is SVG and svg is added to your formats array), we will skip all of the raster formats even if they’re in formats. This may be useful in a CMS-driven workflow when the input could be vector or raster.

• svgShortCircuit: false (default)
• svgShortCircuit: true

Allow SVG to upscale New in Image 0.4.0 #

While we do prevent raster images from upscaling (and filter upscaling widths from the output), you can optionally enable SVG input to upscale to larger sizes when converting to raster format.

• svgAllowUpscale: true (default)
• svgAllowUpscale: false

Use this in your templates #

const Image = require("@11ty/eleventy-img");

async function imageShortcode(src, alt, sizes) {
  let metadata = await Image(src, {
    widths: [300, 600],
    formats: ["avif", "jpeg"]
  });

  let imageAttributes = {
    alt,
    sizes,
    loading: "lazy",
    decoding: "async",
  };

  // You bet we throw an error on missing alt in `imageAttributes` (alt="" works okay)
  return Image.generateHTML(metadata, imageAttributes);
}

module.exports = function(eleventyConfig) {
  eleventyConfig.addNunjucksAsyncShortcode("image", imageShortcode);
  eleventyConfig.addLiquidShortcode("image", imageShortcode);
  eleventyConfig.addJavaScriptFunction("image", imageShortcode);
};

async function imageShortcode(src, alt, sizes) {
  // […]
  return Image.generateHTML(metadata, imageAttributes, {
    whitespaceMode: "inline"
  });
}

// Don’t copy and paste this code block!
// Some code from the above example was removed for brevity.

const Image = require("@11ty/eleventy-img");

async function imageShortcode(src, alt) {
  if(alt === undefined) {
    // You bet we throw an error on missing alt (alt="" works okay)
    throw new Error(`Missing \`alt\` on myImage from: ${src}`);
  }

  let metadata = await Image(src, {
    widths: [600],
    formats: ["jpeg"]
  });

  let data = metadata.jpeg[metadata.jpeg.length - 1];
  return `<img src="${data.url}" width="${data.width}" height="${data.height}" alt="${alt}" loading="lazy" decoding="async">`;
}

module.exports = function(eleventyConfig) {
  eleventyConfig.addNunjucksAsyncShortcode("image", imageShortcode);
  eleventyConfig.addLiquidShortcode("image", imageShortcode);
  eleventyConfig.addJavaScriptFunction("image", imageShortcode);
};

const Image = require("@11ty/eleventy-img");

async function imageShortcode(src, alt, sizes = "100vw") {
  if(alt === undefined) {
    // You bet we throw an error on missing alt (alt="" works okay)
    throw new Error(`Missing \`alt\` on responsiveimage from: ${src}`);
  }

  let metadata = await Image(src, {
    widths: [300, 600],
    formats: ['webp', 'jpeg']
  });

  let lowsrc = metadata.jpeg[0];
  let highsrc = metadata.jpeg[metadata.jpeg.length - 1];

  return `<picture>
    ${Object.values(metadata).map(imageFormat => {
      return `  <source type="${imageFormat[0].sourceType}" srcset="${imageFormat.map(entry => entry.srcset).join(", ")}" sizes="${sizes}">`;
    }).join("\n")}
      <img
        src="${lowsrc.url}"
        width="${highsrc.width}"
        height="${highsrc.height}"
        alt="${alt}"
        loading="lazy"
        decoding="async">
    </picture>`;
}

module.exports = function(eleventyConfig) {
  eleventyConfig.addNunjucksAsyncShortcode("image", imageShortcode);
  eleventyConfig.addLiquidShortcode("image", imageShortcode);
  eleventyConfig.addJavaScriptFunction("image", imageShortcode);
};

Now you can use it in your templates:

{% image "./src/images/cat.jpg", "photo of my cat" %}
{% image "./src/images/cat.jpg", "photo of my cat", "(min-width: 30em) 50vw, 100vw" %}

{% image "./src/images/cat.jpg", "photo of my cat" %}
{% image "./src/images/cat.jpg", "photo of my cat", "(min-width: 30em) 50vw, 100vw" %}

module.exports = function() {
  return `<h1>${await this.image("./src/images/cat.jpg", "photo of my cat", "(min-width: 30em) 50vw, 100vw")}</h1>`;
};

And you’ll have the appropriate HTML generated for you (based on your specified Image options).

Synchronous Usage #

Use Image.statsSync to get the metadata of a source even if the image
generation is not finished yet:

const Image = require("@11ty/eleventy-img");
function imageShortcode(src, cls, alt, sizes, widths) {
  let options = {
    widths: widths,
    formats: ['jpeg'],
  };

  // generate images, while this is async we don’t wait
  Image(src, options);

  let imageAttributes = {
    class: cls,
    alt,
    sizes,
    loading: "lazy",
    decoding: "async",
  };
  // get metadata even the images are not fully generated
  let metadata = Image.statsSync(src, options);
  return Image.generateHTML(metadata, imageAttributes);
}

module.exports = function(eleventyConfig) {
  eleventyConfig.addNunjucksShortcode("myImage", imageShortcode);
}

Advanced control of Sharp image processor #

Extra options to pass to the Sharp constructor or the Sharp image format converter for webp, png, jpeg, or avif.

• sharpOptions: {} New in Image 0.4.0
• sharpWebpOptions: {} New in Image 0.4.2
• sharpPngOptions: {} New in Image 0.4.2
• sharpJpegOptions: {} New in Image 0.4.2
• sharpAvifOptions: {} New in Image 0.6.0

Custom Filenames New in Image 0.4.0 #

Don’t like those hash ids? Make your own!

{
  // Define custom filenames for generated images
  filenameFormat: function (id, src, width, format, options) {
    // id: hash of the original image
    // src: original image path
    // width: current width in px
    // format: current file format
    // options: set of options passed to the Image call

    return `${id}-${width}.${format}`;
  }
}

const path = require("path");
const Image = require("@11ty/eleventy-img");

await Image("./test/bio-2017.jpg", {
  widths: [300],
  formats: [null],
  filenameFormat: function (id, src, width, format, options) {
    const extension = path.extname(src);
    const name = path.basename(src, extension);

    return `${name}-${width}w.${format}`;
  }
});

// Writes: "test/img/bio-2017-300w.jpeg"

Caching #

In-Memory Cache New in Image 0.7.0 #

To prevent duplicate work and improve build performance, repeated calls to the same source image (remote or local) with the same options will return a cached results object. If a request in-progress, the pending promise will be returned. This in-memory cache is maintained across builds in watch/serve mode.

Images will be regenerated (and the cache ignored) if:

• The source image file size changes (on local image files)
• The cache asset duration expires (for remote images).

You can disable this behavior by using the useCache boolean option:

• useCache: true (default)
• useCache: false to bypass the cache and generate a new image every time.

Examples

const Image = require("@11ty/eleventy-img");

(async () => {
  let stats1 = Image("./test/bio-2017.jpg");
  let stats2 = Image("./test/bio-2017.jpg");

  console.assert(stats1 === stats2, "The same promise");
})();

const Image = require("@11ty/eleventy-img");

(async () => {
  let stats1 = Image("./test/bio-2017.jpg");
  let stats2 = Image("./test/bio-2017.jpg", { widths: [300] });

  console.assert(stats1 !== stats2, "A different promise");
})();

Disk Cache New in Image 1.0.0 #

Starting in Eleventy Image 1.0 (when using the built-in hashing algorithm and not custom filenames), Eleventy will skip processing files that are unchanged and already exist in the output directory. While the previously available in-memory cache avoided processing across repeat builds during --watch and --serve, this will avoid processing unchanged files for all builds. Read more at Issue #51.

Dry-Run New in Image 0.7.0 #

If you want to try it out and not write any files (useful for testing), use the dryRun option.

• dryRun: false (default)
• dryRun: true

Change Global Plugin Concurrency #

const Image = require("@11ty/eleventy-img");
Image.concurrency = 4; // default is 10

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