// vue compiler module for transforming `img:srcset` to a number of `require`s const urlToRequire = require('../url-to-require') module.exports = () => ({ postTransformNode: node => { transform(node) } }) function transform (node) { const tags = ['img', 'source'] if (tags.indexOf(node.tag) !== -1 && node.attrs) { node.attrs.forEach(attr => { if (attr.name === 'srcset') { // same logic as in transform-require.js const value = attr.value const isStatic = value.charAt(0) === '"' && value.charAt(value.length - 1) === '"' if (!isStatic) { return } // http://w3c.github.io/html/semantics-embedded-content.html#ref-for-image-candidate-string-5 const escapedSpaceCharacters = /( |\\t|\\n|\\f|\\r)+/g const imageCandidates = value.substr(1, value.length - 2).split(',').map(s => { // The attribute value arrives here with all whitespace, except normal spaces, represented by escape sequences const [url, descriptor] = s.replace(escapedSpaceCharacters, ' ').trim().split(' ', 2) return { require: urlToRequire(url), descriptor: descriptor } }) // "require(url1)" // "require(url1) 1x" // "require(url1), require(url2)" // "require(url1), require(url2) 2x" // "require(url1) 1x, require(url2)" // "require(url1) 1x, require(url2) 2x" const code = imageCandidates.map( ({ require, descriptor }) => `${require} + "${descriptor ? ' ' + descriptor : ''}, " + ` ).join('').slice(0, -6).concat('"').replace(/ \+ ""$/, '') attr.value = code } }) } }