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Kendo UI Draggable

A repository for the cross-platform abstraction for drag sequences.

Overview

The Kendo UI Draggable component handles mouse drags and touch sequences on mobile devices.

A drag sequence means:

  • Mouse click, drag, release for desktop devices.
  • Touch press, drag, release for mobile devices.

Installation

The library is published as a scoped NPM package in the NPMJS Telerik account.

npm install --save '@progress/kendo-draggable';

Basic Usage

The draggable class constructor accepts an object with three optional event handler callbacks—press, drag, and release.

import Draggable from '@progress/kendo-draggable';

const draggable = new Draggable({
    press: function(e) {
        console.log("pressed", e.pageX, e.pageY);
    },
    drag: function(e) {
        console.log("drag", e.pageX, e.pageY);
    },
    release: function(e) {
        console.log("release", e.pageX, e.pageY);
    }
});

draggable.bindTo(document.getElementById("my-element"));

The Draggable may be re-bound to another element—the event handlers will be automatically unbound from the previous one.

draggable.bindTo(document.getElementById("another-element"));

The draggable object persists a reference to the currently bound element. That is why it should be destroyed when or if the corresponding element is removed from the document.

draggable.destroy();

Features

The Kendo UI Draggable supports:

  • Mouse events
  • Touch events
  • Pointer events
  • Handling of multiple touches. Rather, not getting confused by them.

Dragging on iOS/Android

Handling the drag sequence on mobile devices may require the disabling of the touch-based scrolling. The Draggable will not do that out of the box. The recommended way to handle this issue is by setting a touch-action CSS property. Depending on the type of drags that are handled, you may need touch-action: none, touch-action: pan-y, or touch-action: pan-x.

The touch-action setting does not work for iOS yet. While the iOS 9.3 version, which has been released recently, provides limited support, pan-x and pan-y do not work. To disable the touch-based scrolling in iOS, prevent the touchstart event:

    <div ontouchstart="return false">
        <div id="my-draggable-element"></div>
    </div>

Preventing Selection

The dragging of elements that contain text activates the browser text selection, which, in most cases, is not desirable. To avoid this behavior, use the user-select: none CSS property with its respective browser prefixes.

Mouse-Only mode

To ignore all touch and pointer events, set mouseOnly to true. This is useful when you want to keep the default touch-drag behavior, e.g. horizontal scroll.

import Draggable from '@progress/kendo-draggable';

const draggable = new Draggable({
    mouseOnly: true,
    press: function(e) {
        console.log("pressed", e.pageX, e.pageY);
    },
    drag: function(e) {
        console.log("drag", e.pageX, e.pageY);
    },
    release: function(e) {
        console.log("release", e.pageX, e.pageY);
    }
});

draggable.bindTo(document.getElementById("my-element"));

Browser Support

  • Google Chrome
  • Firefox
  • Safari (OS X)
  • Safari (iOS)
  • Chrome (Android)
  • IE/Edge