index.js

var React = require('react');

var Dropzone = React.createClass({
  getDefaultProps: function() {
    return {
      supportClick: true,
      multiple: true,
      inputName: 'fileInput'
    };
  },

  getInitialState: function() {
    return {
      isDragActive: false
    };
  },

  propTypes: {
    onDrop: React.PropTypes.func.isRequired,
    onDragOver: React.PropTypes.func,
    onDragLeave: React.PropTypes.func,
    size: React.PropTypes.number,
    style: React.PropTypes.object,
    supportClick: React.PropTypes.bool,
    accept: React.PropTypes.string,
    multiple: React.PropTypes.bool
  },

  onDragLeave: function(e) {
    this.setState({
      isDragActive: false
    });

    if (this.props.onDragLeave) {
      this.props.onDragLeave(e);
    }
  },

  onDragOver: function(e) {
    e.preventDefault();
    e.stopPropagation();
    e.dataTransfer.dropEffect = 'copy';

    this.setState({
      isDragActive: true
    });

    if (this.props.onDragOver) {
      this.props.onDragOver(e);
    }
  },

  onDrop: function(e) {
    e.preventDefault();

    this.setState({
      isDragActive: false
    });

    var files;
    if (e.dataTransfer) {
      files = e.dataTransfer.files;
    } else if (e.target) {
      files = e.target.files;
    }

    var maxFiles = (this.props.multiple) ? files.length : 1;
    for (var i = 0; i < maxFiles; i++) {
      files[i].preview = URL.createObjectURL(files[i]);
    }

    if (this.props.onDrop) {
      files = Array.prototype.slice.call(files, 0, maxFiles);
      this.props.onDrop(files, e);
    }
  },

  onClick: function () {
    if (this.props.supportClick === true) {
      this.open();
    }
  },

  open: function() {
    var fileInput = React.findDOMNode(this.refs.fileInput);
    fileInput.value = null;
    fileInput.click();
  },

  render: function() {

    var className = this.props.className || 'dropzone';
    if (this.state.isDragActive) {
      className += ' active';
    }

    var style = this.props.style || {
      width: this.props.size || 100,
      height: this.props.size || 100,
      borderStyle: this.state.isDragActive ? 'solid' : 'dashed'
    };


    return (
        React.createElement('div', {className: className, style: style, onClick: this.onClick, onDragLeave: this.onDragLeave, onDragOver: this.onDragOver, onDrop: this.onDrop},
            React.createElement('input', {style: {display: 'none'}, type: 'file', multiple: this.props.multiple, name: this.props.inputName, ref: 'fileInput', onChange: this.onDrop, accept: this.props.accept}),
            this.props.children
        )
    );
  }

});

module.exports = Dropzone;