react-draggable

A simple component for making elements draggable.

Demo

Installing

$ npm install react-draggable

If you aren't using browserify/webpack, a UMD version of react-draggable is available. It is updated per-release only.

If you want a UMD version of the latest master revision, you can generate it yourself from master by cloning this repository and running $ make. This will create umd dist files in the dist/ folder.

Details

A <Draggable> element wraps an existing element and extends it with new event handlers and styles. It does not create a wrapper element in the DOM.

Draggable items are moved using CSS Transforms. This allows items to be dragged regardless of their current positioning (relative, absolute, or static). Elements can also be moved between drags without incident.

If the item you are dragging already has a CSS Transform applied, it will be overwritten by <Draggable>. Use an intermediate wrapper (<Draggable><span>...</span></Draggable>) in this case.

API

The <Draggable/> component transparently adds draggable to whatever element is supplied as this.props.children. Note: Only a single element is allowed or an Error will be thrown.

For the <Draggable/> component to correctly attach itself to its child, the child element must provide support for the following props:

style is used to give the transform css to the child.
className is used to apply the proper classes to the object being dragged.
onMouseDown is used along with onMouseUp to keep track of dragging state.
onMouseUp is used along with onMouseDown to keep track of dragging state.
onTouchStart is used along with onTouchEnd to keep track of dragging state.
onTouchEnd is used along with onTouchStart to keep track of dragging state.

React.DOM elements support the above six properties by default, so you may use those elements as children without any changes. If you wish to use a React component you created, you might find this React page helpful.

Props:

axis: determines which axis the draggable can move. Accepted values:

both allows movement horizontally and vertically (default).
x limits movement to horizontal axis.
y limits movement to vertical axis.

handle: specifies a selector to be used as the handle that initiates drag.

cancel: specifies a selector to be used to prevent drag initialization.

grid: specifies the x and y that dragging should snap to.

bounds: specifies movement boundaries. Accepted values:

parent restricts movement within the node's offsetParent (nearest node with position relative or absolute), or
An object with left, top, right, and bottom properties. These indicate how far in each direction the draggable can be moved. See example/index.html for more on this.

start: specifies the x and y that the dragged item should start at. This is generally not necessary to use (you can use absolute or relative positioning of the child directly), but can be helpful for uniformity in your callbacks and with css transforms.

moveOnStartChange: if true (it defaults false), will move the element if there is a change in start. It won't work if the start is changed in the middle of a drag. We set this by default to false because it can cause unwanted effects if you are not aware of it.

zIndex: specifies the zIndex to use while dragging.

onStart: called when dragging starts.

onDrag: called while dragging.

onStop: called when dragging stops.

Example usage

/** @jsx React.DOM */
var React = require('react'),
	ReactDOM = require('react-dom'),
	Draggable = require('react-draggable');

var App = React.createClass({
	handleStart: function (event, ui) {
		console.log('Event: ', event);
		console.log('Position: ', ui.position);
	},

	handleDrag: function (event, ui) {
		console.log('Event: ', event);
        console.log('Position: ', ui.position);
	},

	handleStop: function (event, ui) {
		console.log('Event: ', event);
        console.log('Position: ', ui.position);
	},

	render: function () {
		return (
			<Draggable
				axis="x"
				handle=".handle"
				start={{x: 0, y: 0}}
				moveOnStartChange={false}
				grid={[25, 25]}
				zIndex={100}
				onStart={this.handleStart}
				onDrag={this.handleDrag}
				onStop={this.handleStop}>
				<div>
					<div className="handle">Drag from here</div>
					<div>This readme is really dragging on...</div>
				</div>
			</Draggable>
		);
	}
});

ReactDOM.render(<App/>, document.body);

State Problems?

<Draggable> is a stateful component. This means that it is storing its current drag offsets in its internal state. This can cause problems with certain integrations. For example, if you change the position of the element manually, <Draggable> can get into trouble as it assumes a translation in the DOM. If you see an element jump around the page when you click it, this is affecting you.

This is an unfortunate side-effect of dragging, which is inherently stateful.

If you move the element manually, you have two options:

Feed the <Draggable> an x and y parameter in the start param, and change it as you go while setting moveOnStartChange to true, or,
When moving the <Draggable>, ref the element and call resetState().

You can't update the start position during a drag. See #94.

Dragging images

The HTML5 Drag & Drop API can interact strangely with <Draggable>, especially on <img> tags.

If you want an <img> to be draggable, set <img draggable="false" />. See the corresponding issue.

Contributing

Fork the project
Run the project in development mode: $ make dev
Make changes.
Add appropriate tests
$ make test
If tests don't pass, make them pass.
Update README with appropriate docs.
Commit and PR

Release checklist

Update CHANGELOG
make release-patch, make release-minor, or make-release-major
make publish

License

MIT

cllu/react-draggable