ui/node_modules/d3-selection/src/selection/selectChildren.js

import {childMatcher} from "../matcher.js";

var filter = Array.prototype.filter;

function children() {
  return Array.from(this.children);
}

function childrenFilter(match) {
  return function() {
    return filter.call(this.children, match);
  };
}

export default function(match) {
  return this.selectAll(match == null ? children
      : childrenFilter(typeof match === "function" ? match : childMatcher(match)));
}