svgo/plugins/removeUnknownsAndDefaults.js

'use strict';

const { parseName } = require('../lib/svgo/tools.js');

exports.name = 'removeUnknownsAndDefaults';

exports.type = 'perItem';

exports.active = true;

exports.description =
  'removes unknown elements content and attributes, removes attrs with default values';

exports.params = {
  unknownContent: true,
  unknownAttrs: true,
  defaultAttrs: true,
  uselessOverrides: true,
  keepDataAttrs: true,
  keepAriaAttrs: true,
  keepRoleAttr: false,
};

var collections = require('./_collections'),
  elems = collections.elems,
  attrsGroups = collections.attrsGroups,
  elemsGroups = collections.elemsGroups,
  attrsGroupsDefaults = collections.attrsGroupsDefaults,
  attrsInheritable = collections.inheritableAttrs,
  applyGroups = collections.presentationNonInheritableGroupAttrs;

// collect and extend all references
for (const elem of Object.values(elems)) {
  if (elem.attrsGroups) {
    elem.attrs = elem.attrs || [];

    elem.attrsGroups.forEach(function (attrsGroupName) {
      elem.attrs = elem.attrs.concat(attrsGroups[attrsGroupName]);

      var groupDefaults = attrsGroupsDefaults[attrsGroupName];

      if (groupDefaults) {
        elem.defaults = elem.defaults || {};

        for (const [attrName, attr] of Object.entries(groupDefaults)) {
          elem.defaults[attrName] = attr;
        }
      }
    });
  }

  if (elem.contentGroups) {
    elem.content = elem.content || [];

    elem.contentGroups.forEach(function (contentGroupName) {
      elem.content = elem.content.concat(elemsGroups[contentGroupName]);
    });
  }
}

/**
 * Remove unknown elements content and attributes,
 * remove attributes with default values.
 *
 * @param {Object} item current iteration item
 * @param {Object} params plugin params
 * @return {Boolean} if false, item will be filtered out
 *
 * @author Kir Belevich
 */
exports.fn = function (item, params) {
  // elems w/o namespace prefix
  if (item.type === 'element' && !parseName(item.name).prefix) {
    var elem = item.name;

    // remove unknown element's content
    if (
      params.unknownContent &&
      elems[elem] && // make sure we know of this element before checking its children
      elem !== 'foreignObject' // Don't check foreignObject
    ) {
      item.children.forEach(function (content, i) {
        if (
          content.type === 'element' &&
          !parseName(content.name).prefix &&
          ((elems[elem].content && // Do we have a record of its permitted content?
            elems[elem].content.indexOf(content.name) === -1) ||
            (!elems[elem].content && // we dont know about its permitted content
              !elems[content.name])) // check that we know about the element at all
        ) {
          item.children.splice(i, 1);
        }
      });
    }

    // remove element's unknown attrs and attrs with default values
    if (elems[elem] && elems[elem].attrs) {
      for (const [name, value] of Object.entries(item.attributes)) {
        const { prefix } = parseName(name);
        if (
          name !== 'xmlns' &&
          (prefix === 'xml' || !prefix) &&
          (!params.keepDataAttrs || name.indexOf('data-') != 0) &&
          (!params.keepAriaAttrs || name.indexOf('aria-') != 0) &&
          (!params.keepRoleAttr || name != 'role')
        ) {
          if (
            // unknown attrs
            (params.unknownAttrs && elems[elem].attrs.indexOf(name) === -1) ||
            // attrs with default values
            (params.defaultAttrs &&
              item.attributes.id == null &&
              elems[elem].defaults &&
              elems[elem].defaults[name] === value &&
              (attrsInheritable.includes(name) === false ||
                !item.parentNode.computedAttr(name))) ||
            // useless overrides
            (params.uselessOverrides &&
              item.attributes.id == null &&
              applyGroups.includes(name) === false &&
              attrsInheritable.includes(name) === true &&
              item.parentNode.computedAttr(name, value))
          ) {
            delete item.attributes[name];
          }
        }
      }
    }
  }
};