Javascript Vue

A vue library for drag and drop8 min read

Vue drag-n-drop

A fast and lightweight drag&drop, sortable library for Vue.js with many configuration options covering many d&d scenarios.

This library consists on a wrapper for Vue.js components over the long missed smooth-dnd library. To make it less importee, I moved all the content needed from smooth-dnd to our own library. It’s all plain js now.

This is a forked repo for vue-smooth-dnd that has been stashed for over 2 years.

Installation

npm i vue-dndrop

Example

Vue

<template>
<div>
<div class=”simple-page”>
<Container @drop=”onDrop”>
<Draggable v-for=”item in items” :key=”item.id”>
<div class=”draggable-item”>
{{item.data}}
</div>
</Draggable>
</Container>
</div>
</div>
</template>

<script>
import { Container, Draggable } from “vue-smooth-dnd”;
import { applyDrag, generateItems } from “./utils”;
export default {
name: “Simple”,
components: { Container, Draggable },
data() {
return {
items: generateItems(50, i => ({ id: i, data: “Draggable ” + i }))
};
},
methods: {
onDrop(dropResult) {
this.items = applyDrag(this.items, dropResult);
}
}
};
</script>

API: Container

Component that contains the draggable elements or components. Each of its children should be wrapped by Draggable component

Properties

Properties define the visual behaviour of the library:

Property
Type
Default
Description

:orientation
string
vertical
Orientation of the container. Can be horizontal or vertical.

:behaviour
string
move
Property to describe weather the dragging item will be moved or copied to target container. Can be move or copy or drop-zone or contain.

:tag
string or NodeDescription
div
See descriptions below

:group-name
string
undefined
Draggables can be moved between the containers having the same group names. If not set container will not accept drags from outside. This behaviour can be overriden by shouldAcceptDrop function. See below.

:lock-axis
string
undefined
Locks the movement axis of the dragging. Possible values are x, y or undefined.

:drag-handle-selector
string
undefined
Css selector to test for enabling dragging. If not given item can be grabbed from anywhere in its boundaries.

:non-drag-area-selector
string
undefined
Css selector to prevent dragging. Can be useful when you have form elements or selectable text somewhere inside your draggable item. It has a precedence over dragHandleSelector.

:drag-begin-delay
number
0 (200 for touch devices)
Time in milisecond. Delay to start dragging after item is pressed. Moving cursor before the delay more than 5px will cancel dragging.

:animation-duration
number
250
Animation duration in milisecond. To be consistent this animation duration will be applied to both drop and reorder animations.

:auto-scroll-enabled
boolean
true
First scrollable parent will scroll automatically if dragging item is close to boundaries.

:drag-class
string
undefined
Class to be added to the ghost item being dragged. The class will be added after it’s added to the DOM so any transition in the class will be applied as intended.

:drop-class
string
undefined
Class to be added to the ghost item just before the drop animation begins.

:remove-on-drop-out
boolean
undefined
When set true onDrop will be called with a removedIndex if you drop element out of any relevant container

:drop-placeholder
boolean,object
undefined
Options for drop placeholder. className, animationDuration, showOnTop

tag

Tag name or the node definition to render the root element of the Container.
Default value is ‘div’.

:tag=”{value: ‘table’, props: {class: ‘my-table’}}”

tag = “table”;

possible values

string : The tag name of the root element to be created
object : Node definition

value: string : tag name
props: data object to define element properties. see https://vuejs.org/v2/guide/render-function.html#The-Data-Object-In-Depth

Lifecycle

The lifecycle of a drag is both described, and can be controlled, by a series of callbacks and events, which are illustrated below for a example containing 3 containers:

Mouse Calls Callback / Event Parameters Notes

down o Initial click

move o Initial drag
|
| get-child-payload() index Function should return payload
|
| 3 x should-accept-drop() srcOptions, payload Fired for all containers
|
| 3 x drag-start dragResult Fired for all containers
|
| drag-enter
v

move o Drag over containers
|
| n x drag-leave Fired as draggable leaves container
| n x drag-enter Fired as draggable enters container
v

up o Finish drag

should-animate-drop() srcOptions, payload Fires once for dropped container

3 x drag-end dragResult Fired for all containers

n x drop dropResult Fired only for droppable containers

Note that should-accept-drop is fired before every drag-start, and before every drag-end, but has been omitted here for clarity.

The dragResult parameter has the format:

dragResult: {
payload,
isSource,
willAcceptDrop,
}

The dropResult parameter has the format:

dropResult: {
addedIndex,
removedIndex,
payload,
droppedElement,
}

Note that additional parameters can be passed to callbacks and event handlers by writing an interim handler inline in the markup:

<div v-for=”(items, index) in groups”
<Container group-name=”column”
:should-accept-drop=”(src, payload) => getShouldAcceptDrop(index, src, payload)”
>

</Container>
</div>

This can provide handler functions context-sensitive data, such as the loop index or current item.

Callbacks

Callbacks provide additional logic and checks before and during user interaction.

get-child-payload()

The function to be called to get the payload object to be passed onDrop function.

<Container :get-child-payload=”getChildPayload”>

getChildPayload (index) {
return {
// generate custom payload data here
}
}

Parameters

index : number : index of the child item

Returns

payload : object

should-accept-drop()

The function to be called by all containers before drag starts to determine the containers to which the drop is possible. Setting this function will override the group-name property and only the return value of this function will be taken into account.

<Container :should-accept-drop=”shouldAcceptDrop”>

shouldAcceptDrop (sourceContainerOptions, payload) {
return true;
}

Parameters

sourceContainerOptions : object : options of the source container. (parent container of the dragged item)
payload : object : the payload object retrieved by calling get-child-payload function.

Returns

boolean : true / false

should-animate-drop()

The function to be called by the target container to which the dragged item will be dropped.
Sometimes dragged item’s dimensions are not suitable with the target container and dropping animation can be wierd. So it can be disabled by returning false. If not set drop animations are enabled.

<Container :should-animate-drop=”shouldAnimateDrop”>

shouldAnimateDrop (sourceContainerOptions, payload) {
return false;
}

Parameters

sourceContainerOptions : object : options of the source container. (parent container of the dragged item)
payload : object : the payload object retrieved by calling get-child-payload function.

Returns

boolean : true / false

get-ghost-parent()

The function to be called to get the element that the dragged ghost will be appended. Default parent element is the container itself.
The ghost element is positioned as ‘fixed’ and appended to given parent element.
But if any anchestor of container has a transform property, ghost element will be positioned relative to that element which breaks the calculations. Thats why if you have any transformed parent element of Containers you should set this property so that it returns any element that has not transformed parent element.

<Container :get-ghost-parent=”getGhostParent”>

getGhostParent() {
// i.e return document.body;
}

Returns

Element : Any DOM element that the ghost will be appended in

Events

Events may call user-defined handlers at particular points in the drag-and-drop lifecycle.

@drag-start

Event to be emitted by all containers on drag start.

<Container @drag-start=”onDragStart”>

onDragStart (dragResult) {
const { isSource, payload, willAcceptDrop } = dragResult
}

Parameters

dragResult : object

payload : object : the payload object that is returned by get-child-payload. It will be undefined in case get-child-payload is not set.
isSource : boolean : true if it is called by the container which drag starts from otherwise false.
willAcceptDrop : boolean : true if the dragged item can be dropped into the container, otherwise false.

@drag-end

The function to be called by all containers on drag end. Called before drop event.

<Container @drag-end=”onDragEnd”>

onDragEnd (dragResult) {
const { isSource, payload, willAcceptDrop } = dragResult
}

Parameters

dragResult : object

isSource : boolean : true if it is called by the container which drag starts from, otherwise false.
payload : object : the payload object that is returned by get-child-payload function. It will be undefined in case get-child-payload is not set.
willAcceptDrop : boolean : true if the dragged item can be dropped into the container, otherwise false.

@drag-enter

The event to be emitted by the relevant container whenever a dragged item enters its boundaries while dragging.

<Container @drag-enter=”onDragEnter”>

onDragEnter () {

}

@drag-leave

The event to be emitted by the relevant container whenever a dragged item leaves its boundaries while dragging.

<Container @drag-leave=”onDragLeave”>

onDragLeave () {

}

@drop-ready

The function to be called by the container which is being drag over, when the index of possible drop position changed in container. Basically it is called each time the draggables in a container slides for opening a space for dragged item. dropResult is the only parameter passed to the function which contains the following properties.

<Container @drop-ready=”onDropReady”>

onDropReady(dropResult) {
const { removedIndex, addedIndex, payload, element } = dropResult;

}

Parameters

dropResult : object

removedIndex : number : index of the removed children. Will be null if no item is removed.
addedIndex : number : index to add droppped item. Will be null if no item is added.
payload : object : the payload object retrieved by calling getChildPayload function.
element : DOMElement : the DOM element that is moved

@drop

The event to be emitted by any relevant container when drop is over. (After drop animation ends). Source container and any container that could accept drop is considered relevant.

<Container @drop=”onDrop”>

onDrop (dropResult) {
const { removedIndex, addedIndex, payload, element } = dropResult;

}

Parameters

dropResult : object

removedIndex : number : index of the removed child. Will be null if no item is removed.
addedIndex : number : index to add dropped item. Will be null if no item is added.
payload : object : the payload object retrieved by calling get-child-payload function.
droppedElement : DOMElement : the DOM element that is moved

API: Draggable

Wrapper component for Container’s children. Every child element should be wrapped with Draggable component.

Properties

tag

Tag name or the node definition to render the root element of the Draggable.
Default value is ‘div’.

:tag=”{value: ‘tr’, props: {class: ‘my-table-row’}}”

tag = “tr”;

possible values

string : The tag name of the root element to be created
object : Node definition

value: string : tag name
props: data object to define element properties. see https://vuejs.org/v2/guide/render-function.html#The-Data-Object-In-Depth

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