srcset

Parse and stringify the HTML <img> srcset attribute.

Can be useful if you're creating a build-tool.

Install

npm install srcset

Usage

How an image with srcset might look like:

<img
    alt="The Breakfast Combo"
    src="banner.jpg"
    srcset="banner-HD.jpg 2x, banner-phone.jpg 100w"
>

Then have some fun with it:

import {parseSrcset, stringifySrcset} from 'srcset';

const parsed = parseSrcset('banner-HD.jpg 2x, banner-phone.jpg 100w');
console.log(parsed);
/*
[
    {
        url: 'banner-HD.jpg',
        density: 2
    },
    {
        url: 'banner-phone.jpg',
        width: 100
    }
]
*/

parsed.push({
    url: 'banner-super-HD.jpg',
    density: 3
});

const stringified = stringifySrcset(parsed);
console.log(stringified);
/*
banner-HD.jpg 2x, banner-phone.jpg 100w, banner-super-HD.jpg 3x
*/

API

parseSrcset(string, options?)

Parse the HTML <img> srcset attribute.

Accepts a “srcset” string and returns an array of objects with the possible properties: url (always), width, height, and density.

string

Type: string

A “srcset” string.

options

Type: object

strict

Type: boolean
Default: false

When enabled, an invalid “srcset” string will cause an error to be thrown. When disabled, a best effort will be made to parse the string, potentially resulting in invalid or nonsensical output.

stringifySrcset(SrcSetDefinitions, options?)

Stringify SrcSetDefinitions. Accepts an array of SrcSetDefinition objects and returns a “srcset” string.

srcsetDescriptors

Type: array

An array of SrcSetDefinition objects. Each object should have a url field and may have width, height or density fields. When the strict option is true, only width or density is accepted.

options

Type: object

strict

Type: boolean
Default: false

Enable or disable validation of the SrcSetDefinition's. When true, invalid input will cause an error to be thrown. When false, a best effort will be made to stringify invalid input, likely resulting in invalid srcset value.