Vue Virtualised

Vue components developed by Vue.js 3.0 for efficiently rendering large scrollable lists and hierarchical data. vue-virtualised is able to render and update 1 million nodes within a few seconds in front-end.

Getting started

Install vue-virtualised using npm.

# npm
npm install vue-virtualised --save

# yarn
yarn add vue-virtualised

ES6 and CommonJS builds are available with each distribution. For example:

// You can import any component you want as a named export from 'vue-virtualised'. e.g.
import { VirtualisedList, VirtualisedTree } from "vue-virtualised";

// Or you can import the component as a named export. e.g.
import { VirtualisedTree as Tree } from "vue-virtualised";

Usage

VirtualisedList usage

<virtualised-list :nodes="[1, 2, 3, 4, 5]">
  <template #cell="slotProps">
    {{ slotProps.node }}
  </template>
</virtualised-list>

VirtualisedTree usage

<virtualised-tree
  :nodes="[
    {
      name: 'Node 1',
      children: [{ name: 'Leaf 1' }],
      state: { expanded: true },
    },
    { name: 'Node 2' },
  ]"
>
  <template #cell="slotProps">
    <!-- node.parents is an array that contains all parent nodes' index -->
    <div
      :style="{
        textAlign: 'left',
        marginLeft: `${slotProps.node.parents.length * 30}px`,
      }"
    >
      {{ slotProps.node.name }}
    </div>
  </template>
</virtualised-tree>

Types

A static type system can help prevent many potential runtime errors as applications grow, which is why this project is written in TypeScript. When the documentation is referred to any specific type, please check types folder for more information. For TypeScript project, types can be imported directly from the library. For example:

import type { Node, NodeModel } from "vue-virtualised";

Props

Mutual props

Here are props that are identical in both VirtualisedList and VirtualisedTree components.

Prop	Type	Required?	Default	Description
viewportHeight	Number		400	The height (px) of the scrollable container for rendering elements.
initialScrollTop	Number		0	The initial scroll position (px).
initialScrollIndex	Number		0	The initial scroll index. If this prop is specified, it will override initialScrollTop prop.
scrollBehaviour	String		auto	Inherited from ScrollToOptions.behavior that specifies whether the scrolling should animate smoothly, or happen instantly in a single jump. Value is an enum, which can be one of the following: smooth: The scrolling animates smoothly. auto: The scrolling happens in a single jump.
tolerance	Number		2	Padding of nodes outside of the viewport to allow for smooth scrolling.
getNodeHeight	GetNodeHeight		(node) => 40	A function that takes the current node as a parameter, and returns the height (px) of the node. e.g. (node) => 30 + (node.index % 10)
getNodeKey	GetNodeKey			A function that takes the current node and the index of the node in the virtual scroller as parameters, and returns the value of key prop of the node renderer. Key is a unique identifier for the virtualised scroller. e.g. (node, index) => node.key Note that the return value is not necessarily the same as node.key, and it is used to identify each Vue list element.
cellRenderer	CellRenderer			A function that takes the current node and its current index in the virtualised scroller as parameters, and returns an array of Children VNodes, built using h(), or using strings to get "text VNodes" or an object with slots. If this prop is specified, the cell slot in the template will be override. e.g. (node, index) => [h("div", {style: {height: "100%"}}, node.name)]

VirtualisedList props

Prop	Type	Required?	Default	Description
nodes	Array<any>	✓		List data for rendering and can be any types inside of the array.

VirtualisedTree props

Prop	Type	Required?	Default	Description
nodes	Array<Node>	✓		Tree data with implementing the following keys: name: The primary label for the node. state?: An object stores states of each node. expanded?: shows children of the node if true, or hides them if false. Defaults to false. children: An array of child nodes belonging to the node. e.g. [{name: "Node 1", children: [{name: "Leaf 1"}]}, {name: "Node 2"}]
useTimeSlicing	boolean		false	Time slicing is a technique allows for switching between macro tasks (i.e. DOM redrawing) and micro tasks (i.e. node updating inside an iteration) when traversing and manipulating enormous amount of nodes. If it's set to true, we can avoid blocking the whole web application during the process. However, the total amount of traversal time will be longer because the application will switch between macro and micro tasks.
onChange	OnChangeCallback			A function that takes nodes prop as a parameter. This function will be called when executing updateNode() and updateNodes() methods.

Events

Mutual events

Here are events that are identical in both VirtualisedList and VirtualisedTree components.

Event	Description
onScroll	Triggered when the user is scrolling the rendered content. This event emits the current scroll position of the rendered content.
onStartReached	Triggered once when the scroll position gets the bottom of the rendered content. This event emits the current scroll position of the rendered content.
onEndReached	Triggered once when the scroll position gets the top of the rendered content. This event emits the current scroll position of the rendered content.

Slots

Mutual slots

Slots are provided for rendering content dynamically. Here are slots that are identical in both VirtualisedList and VirtualisedTree components.

Slot	Props	Description
cell	node: The current node for rendering with type NodeModel. index: The current index of the node in children of its parent node. parents: An array of indices of all parent nodes ordered from the root node. key: A unique identifier of the node, consists of the node's path. e.g. The node with the path [0, 1] has the key of 0,1. name: The name of the node. state: An object stores states of each node. expanded: shows children of the node if true, or hides them if false. isLeaf: A boolean that indicates if the current node is the leaf node. children: An array of child nodes belonging to the node. index: The current node's index in the rendered content.	The slot for rendering a single node in the content. If cellRenderer props is specified, this slot won't have effect.

VirtualisedTree slots

Slot	Props	Description
fallback		There are cases when it's useful to specify fallback (i.e. default) content for a slot, to be rendered only when no content is provided. This slot is only available when useTimeSlicing prop sets to true because it takes longer to load the content.

Methods

Mutual methods

scrollToStart()

scrollToStart(): void

scrollToEnd()

scrollToEnd(): void

scrollToIndex()

scrollToIndex(index: number): void

Valid index should be in the range from 0 to nodes.length - 1.

scrollToNode()

scrollToNode(conditionCallback: ConditionCallback): void

Valid conditionCallback should be a function that takes a node as a parameter and returns a boolean:

conditionCallback(node: Node): boolean

VirtualisedList methods

refreshView()

refreshView(): void

Forces refresh rendered content.

VirtualisedTree methods

scrollToHeight()

scrollToHeight(height: number, behaviour: ScrollBehavior): void

createNode(): CreateFunction

createNode(nodes: Array<Node | NodeModel>, node: NodeModel, path: Array<number>): Promise<void>

This method creates a single node (node allows contain children) as well as its descendants, and it can be bound to the cell slot. Valid parameters are:

• nodes: nodes prop.

• node: The node to be created.

• path: The path of the node in the tree structure. e.g. For the following tree structure, the paths are showing in the comment for each:

  [
    {
      name: 'Node 1', // path: [0]
      children: [{ name: 'Leaf 1' /* path: [0, 0] */ }],
      state: { expanded: true },
    },
    { name: 'Node 2' }, // path: [1]
  ]

  In addition, path can be composed by the node slot prop in the cell slot:

  const path = [...node.parents, node.index];

updateNode(): UpdateFunction

updateNode(nodes: Array<Node>, node: NodeModel, index: number, updateFn: UpdateNodeCallback): void

This method can be bound to the cell slot, which updates a single node in both original data and the view. Valid parameters are:

• nodes: nodes prop.
• node: The current node of the slot that needs to be updated.
• index: The index of the node that needs to be updated.
• updateFn: The function that manipulates the current node and returns an updated node:

updateFn(node: NodeModel): NodeModel

This method can be used to expand/collapse the current node by setting the boolean value of state.expanded.

updateNodes(): UpdateFunction

updateNodes(nodes: Array<Node>, node: NodeModel, index: number, updateFn: UpdateNodeCallback): void

This method can be bound to cell slot, which updates a single node in the tree view including all its descendants in both original data and the view. Valid parameters are:

• nodes: nodes prop.
• node: The current node of the slot that needs to be updated.
• index: The index of the node that needs to be updated.
• updateFn: The function that manipulates the current node and returns an updated node:

updateFn(node: NodeModel): NodeModel

removeNode(): RemoveFunction

removeNode(nodes: Array<Node | NodeModel>, path: Array<number>): Promise<void>

This method removes a single node as well as its descendants, and it can be bound to the cell slot. Valid parameters are:

• nodes: nodes prop.
• path: The path of the node in the tree structure.

forceUpdate()

forceUpdate(): void

Forces refresh rendered content.

Contributing

Pull requests and issues are welcome!

Project setup

yarn install

Compiles and hot-reloads for development

yarn serve

Compiles and minifies for production

yarn build

Lints and fixes files

yarn lint

License

MIT