vue hello world项目
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3 years ago
'use strict';
exports.type = 'visitor';
exports.name = 'removeUnusedNS';
exports.active = true;
exports.description = 'removes unused namespaces declaration';
/**
* Remove unused namespaces declaration from svg element
* which are not used in elements or attributes
*
* @author Kir Belevich
*
* @type {import('../lib/types').Plugin<void>}
*/
exports.fn = () => {
/**
* @type {Set<string>}
*/
const unusedNamespaces = new Set();
return {
element: {
enter: (node, parentNode) => {
// collect all namespaces from svg element
// (such as xmlns:xlink="http://www.w3.org/1999/xlink")
if (node.name === 'svg' && parentNode.type === 'root') {
for (const name of Object.keys(node.attributes)) {
if (name.startsWith('xmlns:')) {
const local = name.slice('xmlns:'.length);
unusedNamespaces.add(local);
}
}
}
if (unusedNamespaces.size !== 0) {
// preserve namespace used in nested elements names
if (node.name.includes(':')) {
const [ns] = node.name.split(':');
if (unusedNamespaces.has(ns)) {
unusedNamespaces.delete(ns);
}
}
// preserve namespace used in nested elements attributes
for (const name of Object.keys(node.attributes)) {
if (name.includes(':')) {
const [ns] = name.split(':');
unusedNamespaces.delete(ns);
}
}
}
},
exit: (node, parentNode) => {
// remove unused namespace attributes from svg element
if (node.name === 'svg' && parentNode.type === 'root') {
for (const name of unusedNamespaces) {
delete node.attributes[`xmlns:${name}`];
}
}
},
},
};
};