149 lines
4.3 KiB
JavaScript
149 lines
4.3 KiB
JavaScript
'use strict';
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/**
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* @typedef {import('../lib/types').XastElement} XastElement
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*/
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const csso = require('csso');
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exports.type = 'visitor';
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exports.name = 'minifyStyles';
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exports.active = true;
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exports.description =
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'minifies styles and removes unused styles based on usage data';
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/**
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* Minifies styles (<style> element + style attribute) using CSSO
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*
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* @author strarsis <strarsis@gmail.com>
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*
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* @type {import('../lib/types').Plugin<csso.MinifyOptions & Omit<csso.CompressOptions, 'usage'> & {
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* usage?: boolean | {
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* force?: boolean,
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* ids?: boolean,
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* classes?: boolean,
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* tags?: boolean
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* }
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* }>}
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*/
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exports.fn = (_root, { usage, ...params }) => {
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let enableTagsUsage = true;
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let enableIdsUsage = true;
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let enableClassesUsage = true;
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// force to use usage data even if it unsafe (document contains <script> or on* attributes)
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let forceUsageDeoptimized = false;
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if (typeof usage === 'boolean') {
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enableTagsUsage = usage;
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enableIdsUsage = usage;
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enableClassesUsage = usage;
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} else if (usage) {
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enableTagsUsage = usage.tags == null ? true : usage.tags;
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enableIdsUsage = usage.ids == null ? true : usage.ids;
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enableClassesUsage = usage.classes == null ? true : usage.classes;
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forceUsageDeoptimized = usage.force == null ? false : usage.force;
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}
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/**
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* @type {Array<XastElement>}
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*/
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const styleElements = [];
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/**
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* @type {Array<XastElement>}
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*/
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const elementsWithStyleAttributes = [];
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let deoptimized = false;
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/**
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* @type {Set<string>}
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*/
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const tagsUsage = new Set();
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/**
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* @type {Set<string>}
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*/
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const idsUsage = new Set();
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/**
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* @type {Set<string>}
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*/
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const classesUsage = new Set();
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return {
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element: {
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enter: (node) => {
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// detect deoptimisations
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if (node.name === 'script') {
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deoptimized = true;
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}
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for (const name of Object.keys(node.attributes)) {
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if (name.startsWith('on')) {
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deoptimized = true;
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}
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}
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// collect tags, ids and classes usage
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tagsUsage.add(node.name);
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if (node.attributes.id != null) {
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idsUsage.add(node.attributes.id);
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}
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if (node.attributes.class != null) {
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for (const className of node.attributes.class.split(/\s+/)) {
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classesUsage.add(className);
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}
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}
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// collect style elements or elements with style attribute
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if (node.name === 'style' && node.children.length !== 0) {
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styleElements.push(node);
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} else if (node.attributes.style != null) {
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elementsWithStyleAttributes.push(node);
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}
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},
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},
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root: {
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exit: () => {
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/**
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* @type {csso.Usage}
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*/
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const cssoUsage = {};
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if (deoptimized === false || forceUsageDeoptimized === true) {
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if (enableTagsUsage && tagsUsage.size !== 0) {
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cssoUsage.tags = Array.from(tagsUsage);
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}
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if (enableIdsUsage && idsUsage.size !== 0) {
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cssoUsage.ids = Array.from(idsUsage);
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}
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if (enableClassesUsage && classesUsage.size !== 0) {
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cssoUsage.classes = Array.from(classesUsage);
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}
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}
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// minify style elements
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for (const node of styleElements) {
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if (
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node.children[0].type === 'text' ||
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node.children[0].type === 'cdata'
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) {
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const cssText = node.children[0].value;
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const minified = csso.minify(cssText, {
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...params,
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usage: cssoUsage,
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}).css;
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// preserve cdata if necessary
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// TODO split cdata -> text optimisation into separate plugin
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if (cssText.indexOf('>') >= 0 || cssText.indexOf('<') >= 0) {
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node.children[0].type = 'cdata';
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node.children[0].value = minified;
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} else {
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node.children[0].type = 'text';
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node.children[0].value = minified;
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}
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}
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}
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// minify style attributes
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for (const node of elementsWithStyleAttributes) {
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// style attribute
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const elemStyle = node.attributes.style;
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node.attributes.style = csso.minifyBlock(elemStyle, {
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...params,
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}).css;
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}
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},
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},
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};
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};
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