@prismicio/client/dist/helpers/asImageWidthSrcSet.js

The official JavaScript + TypeScript client library for Prismic

import { imageThumbnail } from "./isFilled.js";
import { buildURL, buildWidthSrcSet } from "imgix-url-builder";

//#region src/helpers/asImageWidthSrcSet.ts
/**
* The default widths used to generate a `srcset` value.
*/
const DEFAULT_WIDTHS = [
	640,
	828,
	1200,
	2048,
	3840
];
/**
* Creates a width-based `srcset` from an image field with optional image
* transformations via imgix URL parameters.
*
* If a `widths` parameter is not given, the following widths (in pixels) will
* be used by default: 640, 750, 828, 1080, 1200, 1920, 2048, 3840.
*
* If the image field contains responsive views, each responsive view can be
* used as a width in the resulting `srcset` by passing `"thumbnails"` as the
* `widths` parameter.
*
* @example
*
* ```ts
* const srcset = asImageWidthSrcSet(document.data.photo, {
* 	widths: [400, 800, 1600],
* 	sat: -100,
* })
* // => {
* //   src: "https://images.prismic.io/repo/image.png?sat=-100",
* //   srcset: "https://images.prismic.io/repo/image.png?sat=-100&width=400 400w, " +
* //           "https://images.prismic.io/repo/image.png?sat=-100&width=800 800w, " +
* //           "https://images.prismic.io/repo/image.png?sat=-100&width=1600 1600w"
* // }
* ```
*
* @param field - An image field (or one of its responsive views) from which to
*   get an image URL.
* @param config - An object of imgix URL API parameters. The `widths` parameter
*   defines the resulting `srcset` widths. Pass `"thumbnails"` to automatically
*   use the field's responsive views.
*
* @returns A `srcset` attribute value for the image field with imgix URL
*   parameters, or `null` if the field is empty.
*
* @see Learn how to optimize images with imgix: {@link https://prismic.io/docs/fields/image}
* @see imgix URL parameters reference: {@link https://docs.imgix.com/apis/rendering}
*/
const asImageWidthSrcSet = (field, config = {}) => {
	if (field && imageThumbnail(field)) {
		let { widths = DEFAULT_WIDTHS,...imgixParams } = config;
		const { url, dimensions, id: _id, alt: _alt, copyright: _copyright, edit: _edit,...responsiveViews } = field;
		const responsiveViewObjects = Object.values(responsiveViews);
		if (widths === "thumbnails" && responsiveViewObjects.length < 1) widths = DEFAULT_WIDTHS;
		return {
			src: buildURL(url, imgixParams),
			srcset: widths === "thumbnails" ? [buildWidthSrcSet(url, {
				...imgixParams,
				widths: [dimensions.width]
			}), ...responsiveViewObjects.map((thumbnail) => {
				return buildWidthSrcSet(thumbnail.url, {
					...imgixParams,
					widths: [thumbnail.dimensions.width]
				});
			})].join(", ") : buildWidthSrcSet(field.url, {
				...imgixParams,
				widths
			})
		};
	} else return null;
};

//#endregion
export { asImageWidthSrcSet };
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