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  <div class="wrapper">


  </div>

const createDOMFromString = domstring => {
  const div = document.createElement("div");
  div.innerHTML = domstring;
  return div;
};

class Component {
  constructor(props) {
    this.props = props;
  }
  setState(state) {
    const oldElem = this.elem;
    this.state = state;
    this._renderDOM();
    if (this.onStateChange) this.onStateChange(oldElem, this.elem);
  }

  _renderDOM() {
    this.elem = createDOMFromString(this.render());
    if (this.onClick) {
      this.elem.addEventListener("click", this.onClick.bind(this));
    }
    return this.elem;
  }
}

class UpVoteButton extends Component {
  constructor(props) {
    super(props);
    this.state = { isUpVoted: false };
  }

  onClick() {
    this.setState({
      isUpVoted: !this.state.isUpVoted
    });
  }

  render() {
    return `
      <button class='upvote-btn' style="background: ${this.props.bgColor}">
      <span class='upvote-text'>${
        this.state.isUpVoted ? "Cancel" : "UpVote"
      }</span>
      <span><i class="fa fa-thumbs-up" aria-hidden="true"></i></span>
      </button>
    `;
  }
}

class DownVoteButton extends Component {
  constructor(props) {
    super(props);
    this.state = {
      isDownVoted: false
    };
  }

  onClick() {
    this.setState({
      isDownVoted: !this.state.isDownVoted
    });
  }
  render() {
    return `
      <button class="downvote-btn" style="background: ${this.props.bgColor}">
      <span class="downvote-text">${
        this.state.isDownVoted ? "Cancel" : "Downvote"
      }</span>
      <span><i class="fa fa-thumbs-down" aria-hidden="true"></i></span>
      </button>
      `;
  }
}

const componentMount = (component, container) => {
  container.appendChild(component._renderDOM());
  component.onStateChange = (oldElem, newElem) => {
    container.insertBefore(newElem, oldElem);
    container.removeChild(oldElem);
  };
};

const wrapper = document.querySelector(".wrapper");
const upVoteButton = new UpVoteButton({ bgColor: "green" });
const downVoteButton = new DownVoteButton({ bgColor: "red" });
componentMount(upVoteButton, wrapper);
componentMount(downVoteButton, wrapper);