feat: add first <ClassList> implementation

package.json

@@ -1,6 +1,6 @@
 {
   "name": "libreact",
-  "version": "0.13.0",
+  "version": "0.14.0",
   "description": "React standard library",
   "main": "lib/index.js",
   "repository": {

src/ClassNames/index.tsx

@@ -0,0 +1,67 @@
+import {Component} from 'react';
+import {render} from 'react-universal-interface';
+import {Inverted} from '../invert';
+import {h} from '../util';
+
+const equalSets = (a: any[], b: any[]) => {
+  if (a.length !== b.length) {
+    return false;
+  }
+
+  const A = [...a].sort();
+  const B = [...b].sort();
+
+  for (let i = 0; i < A.length; i++) {
+    if (A[i] !== B[i]) {
+      return false;
+    }
+  }
+
+  return true;
+};
+
+export interface IClassNamesProps {
+  el?: HTMLElement;
+  list: string[],
+  persist?: boolean;
+}
+
+export class ClassNames extends Component<IClassNamesProps, {}> {
+  componentDidMount () {
+    this.putList(this.props.list);
+  }
+
+  shouldComponentUpdate (props) {
+    return !equalSets(props.list, this.props.list);
+  }
+
+  componentDidUpdate (props) {
+    if (!props.persist) {
+      this.removeList(props.list, props.el);
+    }
+
+    this.putList(this.props.list);
+  }
+
+  componentWillUnmount () {
+    if (!this.props.persist) {
+      this.removeList(this.props.list);
+    }
+  }
+
+  putList (list: string[], el: HTMLElement = this.props.el) {
+    for (const className of list) {
+      el.classList.add(className);
+    }
+  }
+
+  removeList (list: string[], el: HTMLElement = this.props.el) {
+    for (const className of list) {
+      el.classList.remove(className);
+    }
+  }
+
+  render () {
+    return render(this.props, null);
+  }
+}