spee.ch/react/containers/Dropzone/view.jsx

import React from 'react';
import { validateFile } from 'utils/file';
import Preview from 'components/Preview';

class Dropzone extends React.Component {
  constructor (props) {
    super(props);
    this.state = {
      dragOver  : false,
      mouseOver : false,
      dimPreview: false,
    };
    this.handleDrop = this.handleDrop.bind(this);
    this.handleDragOver = this.handleDragOver.bind(this);
    this.handleDragEnd = this.handleDragEnd.bind(this);
    this.handleDragEnter = this.handleDragEnter.bind(this);
    this.handleDragLeave = this.handleDragLeave.bind(this);
    this.handleMouseEnter = this.handleMouseEnter.bind(this);
    this.handleMouseLeave = this.handleMouseLeave.bind(this);
    this.handleClick = this.handleClick.bind(this);
    this.handleFileInput = this.handleFileInput.bind(this);
    this.selectFile = this.selectFile.bind(this);
  }
  handleDrop (event) {
    event.preventDefault();
    this.setState({dragOver: false});
    // if dropped items aren't files, reject them
    const dt = event.dataTransfer;
    console.log('dt', dt);
    if (dt.items) {
      if (dt.items[0].kind == 'file') {
        const droppedFile = dt.items[0].getAsFile();
        this.selectFile(droppedFile);
      }
    }
  }
  handleDragOver (event) {
    event.preventDefault();
  }
  handleDragEnd (event) {
    var dt = event.dataTransfer;
    if (dt.items) {
      for (var i = 0; i < dt.items.length; i++) {
        dt.items.remove(i);
      }
    } else {
      event.dataTransfer.clearData();
    }
  }
  handleDragEnter () {
    this.setState({dragOver: true, dimPreview: true});
  }
  handleDragLeave () {
    this.setState({dragOver: false, dimPreview: false});
  }
  handleMouseEnter () {
    this.setState({mouseOver: true, dimPreview: true});
  }
  handleMouseLeave () {
    this.setState({mouseOver: false, dimPreview: false});
  }
  handleClick (event) {
    event.preventDefault();
    // trigger file input
    document.getElementById('file_input').click();
  }
  handleFileInput (event) {
    event.preventDefault();
    const fileList = event.target.files;
    this.selectFile(fileList[0]);
  }
  selectFile (file) {
    if (file) {
      try {
        validateFile(file); // validate the file's name, type, and size
      } catch (error) {
        return this.props.onFileError(error.message);
      }
      // stage it so it will be ready when the publish button is clicked
      this.props.onFileError(null);
      this.props.onFileSelect(file);
    }
  }
  render () {
    return (
      <div className='row row--tall flex-container--column'>
        <form>
          <input className='input-file' type='file' id='file_input' name='file_input' accept='video/*,image/*' onChange={this.handleFileInput} encType='multipart/form-data' />
        </form>
        <div id='preview-dropzone' className={'row row--padded row--tall dropzone' + (this.state.dragOver ? ' dropzone--drag-over' : '')} onDrop={this.handleDrop} onDragOver={this.handleDragOver} onDragEnd={this.handleDragEnd} onDragEnter={this.handleDragEnter} onDragLeave={this.handleDragLeave} onMouseEnter={this.handleMouseEnter} onMouseLeave={this.handleMouseLeave} onClick={this.handleClick}>
          {this.props.file ? (
            <div>
              <Preview
                dimPreview={this.state.dimPreview}
                file={this.props.file}
                thumbnail={this.props.thumbnail}
              />
              <div id='dropzone-text-holder' className={'flex-container--column flex-container--center-center'}>
                { this.state.dragOver ? (
                  <div id='dropzone-dragover'>
                    <p className='blue'>Drop it.</p>
                  </div>
                ) : (
                  null
                )}
                { this.state.mouseOver ? (
                  <div id='dropzone-instructions'>
                    <p className='info-message-placeholder info-message--failure' id='input-error-file-selection'>{this.props.fileError}</p>
                    <p>Drag & drop image or video here to publish</p>
                    <p className='fine-print'>OR</p>
                    <p className='blue--underlined'>CHOOSE FILE</p>
                  </div>
                ) : (
                  null
                )}
              </div>
            </div>
          ) : (
            <div id='dropzone-text-holder' className={'flex-container--column flex-container--center-center'}>
              { this.state.dragOver ? (
                <div id='dropzone-dragover'>
                  <p className='blue'>Drop it.</p>
                </div>
              ) : (
                <div id='dropzone-instructions'>
                  <p className='info-message-placeholder info-message--failure' id='input-error-file-selection'>{this.props.fileError}</p>
                  <p>Drag & drop image or video here to publish</p>
                  <p className='fine-print'>OR</p>
                  <p className='blue--underlined'>CHOOSE FILE</p>
                </div>
              )}
            </div>
          )}
        </div>
      </div>
    );
  }
};

export default Dropzone;