removeXlink.js•6.18 kB
'use strict';
const { elems } = require('./_collections');
/**
* @typedef {import('../lib/types').XastElement} XastElement
*/
exports.name = 'removeXlink';
exports.description =
'remove xlink namespace and replaces attributes with the SVG 2 equivalent where applicable';
/** URI indicating the Xlink namespace. */
const XLINK_NAMESPACE = 'http://www.w3.org/1999/xlink';
/**
* Map of `xlink:show` values to the SVG 2 `target` attribute values.
*
* @type {Record<string, string>}
* @see https://developer.mozilla.org/docs/Web/SVG/Attribute/xlink:show#usage_notes
*/
const SHOW_TO_TARGET = {
new: '_blank',
replace: '_self',
};
/**
* Elements that use xlink:href, but were deprecated in SVG 2 and therefore
* don't support the SVG 2 href attribute.
*
* @type {Set<string>}
* @see https://developer.mozilla.org/docs/Web/SVG/Attribute/xlink:href
* @see https://developer.mozilla.org/docs/Web/SVG/Attribute/href
*/
const LEGACY_ELEMENTS = new Set([
'cursor',
'filter',
'font-face-uri',
'glyphRef',
'tref',
]);
/**
* @param {XastElement} node
* @param {string[]} prefixes
* @param {string} attr
* @returns {string[]}
*/
const findPrefixedAttrs = (node, prefixes, attr) => {
return prefixes
.map((prefix) => `${prefix}:${attr}`)
.filter((attr) => node.attributes[attr] != null);
};
/**
* Removes XLink namespace prefixes and converts references to XLink attributes
* to the native SVG equivalent.
*
* The XLink namespace is deprecated in SVG 2.
*
* @type {import('./plugins-types').Plugin<'removeXlink'>}
* @see https://developer.mozilla.org/docs/Web/SVG/Attribute/xlink:href
*/
exports.fn = (_, params) => {
const { includeLegacy } = params;
/**
* XLink namespace prefixes that are currently in the stack.
*
* @type {string[]}
*/
const xlinkPrefixes = [];
/**
* Namespace prefixes that exist in {@link xlinkPrefixes} but were overridden
* in a child element to point to another namespace, and so is not treated as
* an XLink attribute.
*
* @type {string[]}
*/
const overriddenPrefixes = [];
/**
* Namespace prefixes that were used in one of the {@link LEGACY_ELEMENTS}.
*
* @type {string[]}
*/
const usedInLegacyElement = [];
return {
element: {
enter: (node) => {
for (const [key, value] of Object.entries(node.attributes)) {
if (key.startsWith('xmlns:')) {
const prefix = key.split(':', 2)[1];
if (value === XLINK_NAMESPACE) {
xlinkPrefixes.push(prefix);
continue;
}
if (xlinkPrefixes.includes(prefix)) {
overriddenPrefixes.push(prefix);
}
}
}
if (
overriddenPrefixes.some((prefix) => xlinkPrefixes.includes(prefix))
) {
return;
}
const showAttrs = findPrefixedAttrs(node, xlinkPrefixes, 'show');
let showHandled = node.attributes.target != null;
for (let i = showAttrs.length - 1; i >= 0; i--) {
const attr = showAttrs[i];
const value = node.attributes[attr];
const mapping = SHOW_TO_TARGET[value];
if (showHandled || mapping == null) {
delete node.attributes[attr];
continue;
}
if (mapping !== elems[node.name]?.defaults?.target) {
node.attributes.target = mapping;
}
delete node.attributes[attr];
showHandled = true;
}
const titleAttrs = findPrefixedAttrs(node, xlinkPrefixes, 'title');
for (let i = titleAttrs.length - 1; i >= 0; i--) {
const attr = titleAttrs[i];
const value = node.attributes[attr];
const hasTitle = node.children.filter(
(child) => child.type === 'element' && child.name === 'title',
);
if (hasTitle.length > 0) {
delete node.attributes[attr];
continue;
}
/** @type {XastElement} */
const titleTag = {
type: 'element',
name: 'title',
attributes: {},
children: [
{
type: 'text',
value,
},
],
};
Object.defineProperty(titleTag, 'parentNode', {
writable: true,
value: node,
});
node.children.unshift(titleTag);
delete node.attributes[attr];
}
const hrefAttrs = findPrefixedAttrs(node, xlinkPrefixes, 'href');
if (
hrefAttrs.length > 0 &&
LEGACY_ELEMENTS.has(node.name) &&
!includeLegacy
) {
hrefAttrs
.map((attr) => attr.split(':', 1)[0])
.forEach((prefix) => usedInLegacyElement.push(prefix));
return;
}
for (let i = hrefAttrs.length - 1; i >= 0; i--) {
const attr = hrefAttrs[i];
const value = node.attributes[attr];
if (node.attributes.href != null) {
delete node.attributes[attr];
continue;
}
node.attributes.href = value;
delete node.attributes[attr];
}
},
exit: (node) => {
for (const [key, value] of Object.entries(node.attributes)) {
const [prefix, attr] = key.split(':', 2);
if (
xlinkPrefixes.includes(prefix) &&
!overriddenPrefixes.includes(prefix) &&
!usedInLegacyElement.includes(prefix) &&
!includeLegacy
) {
delete node.attributes[key];
continue;
}
if (key.startsWith('xmlns:') && !usedInLegacyElement.includes(attr)) {
if (value === XLINK_NAMESPACE) {
const index = xlinkPrefixes.indexOf(attr);
xlinkPrefixes.splice(index, 1);
delete node.attributes[key];
continue;
}
if (overriddenPrefixes.includes(prefix)) {
const index = overriddenPrefixes.indexOf(attr);
overriddenPrefixes.splice(index, 1);
}
}
}
},
},
};
};