content: import React from 'react';
  import { FormattedMessage } from 'react-intl';
  import PropTypes from 'prop-types';
  import Icon from 'mastodon/components/icon';
  import { createPortal } from 'react-dom';
  
  export default class ColumnBackButton extends React.PureComponent {
  
    static contextTypes = {
      router: PropTypes.object,
    };
  
    static propTypes = {
      multiColumn: PropTypes.bool,
    };
  
    handleClick = () => {
      if (window.history && window.history.length === 1) {
        this.context.router.history.push('/');
      } else {
        this.context.router.history.goBack();
      }
    }
  
    render () {
      const { multiColumn } = this.props;
  
      const component = (
        <button onClick={this.handleClick} className='column-back-button'>
          <Icon id='chevron-left' className='column-back-button__icon' fixedWidth />
          <FormattedMessage id='column_back_button.label' defaultMessage='Back' />
        </button>
      );
  
      if (multiColumn) {
        return component;
      } else {
        // The portal container and the component may be rendered to the DOM in
        // the same React render pass, so the container might not be available at
        // the time `render()` is called.
        const container = document.getElementById('tabs-bar__portal');
        if (container === null) {
          // The container wasn't available, force a re-render so that the
          // component can eventually be inserted in the container and not scroll
          // with the rest of the area.
          this.forceUpdate();
          return component;
        } else {
          return createPortal(component, container);
        }
      }
    }
  
  }
  