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https://github.com/lsycxyj/vue-l-lazyload

A lazyload plugin for Vue.js v2.x+.
https://github.com/lsycxyj/vue-l-lazyload

lazyload vue vuejs vuejs2

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A lazyload plugin for Vue.js v2.x+.

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README

        

# vue-l-lazyload

> A lazyload and in-view detection plugin for Vue.js v2.x+.

### Demo
[Live demo](https://rawcdn.githack.com/lsycxyj/vue-l-lazyload/1558559ece69742dc1cf03f972011e62d74cc10d/demo/index.html) or `npm install vue-l-lazyload && npm run startDev` to play it!

### Pull requests are welcome :)

![Build Status](https://travis-ci.org/lsycxyj/vue-l-lazyload.svg?branch=master)
[![Coverage](https://img.shields.io/codecov/c/github/lsycxyj/vue-l-lazyload/master.svg)](https://codecov.io/github/lsycxyj/vue-l-lazyload?branch=master)

## License
LGPL-V3
[![License: LGPL v3](https://img.shields.io/badge/License-LGPL%20v3-blue.svg)](http://www.gnu.org/licenses/lgpl-3.0)

## Features

- No extra dependencies except Vue
- Progressive configuration
- Flexible events to trigger loading
- Lazyload as src attribute and background image are supported
- Customized retry control
- Filters for substitution of url by rules
- Performance boost by event delegation and passive event listener when it's available
- LazyComp for lazy loading child component.
- InViewComp for in-view detection

## Installation

[![vue-l-lazyload](https://nodei.co/npm/vue-l-lazyload.png)](https://npmjs.org/package/vue-l-lazyload)

`npm install vue-l-lazyload`

## Usage
### A simple way:
```javascript
import { VueLLazyload } from 'vue-l-lazyload';
// For smaller production code with tree shaking, I recommend you to import the src instead:
// import { VueLLazyloadLocal: VueLLazyload } from 'vue-l-lazyload/src';
Vue.use(VueLLazyload, {
events: 'scroll'
});
// The root $lazy "Vue.$lazy" will be available after it's been installed
```
```html

```
### A more configurable way:
```javascript
import { VueLLazyload } from 'vue-l-lazyload';
Vue.use(VueLLazyload, config);
```
```html

```

## Vue Plugins
### VueLLazyload
Vue Plugin with global option of registering directive "lazy" and component "lazy-ref".

### VueLLazyloadLocal
Vue Plugin without global option of registering directives or components for local usage purpose and smaller footprint.

## Config

### Notes about Config
Note that **ALL ANCESTORS' CONFIGS WILL BE INHERITED** level by level.
So be careful there may be conflict problems if you use too many ancestors' configs!

### Available Config Table



Name
Type
Default
Description




events
String or Array<String>
scroll

Events to be bound with.



preloadRatio
Number
1

The "resize" ratio of parent view when it's children views compare with it.



onEnter
Function
-

It will be triggered if the element enters the sight. The argument will be a object:

{

// The LazyLoader
$lazy,
}




onLeave
Function
-

It will be triggered if the element leaves the sight. The argument will be a object:
{

// The LazyLoader
$lazy,
}




throttleMethod
String
debounce

Throttling method. Available values: "debounce", "throttle"



throttleTime
Integer
250

Throttling time in ms.



regGlobal
Boolean
true

Whether to register the directive "lazy" and component "lazy-ref" globally or not.

Only available for global config of "VueLLazyload".


[1]: All options will inherit its ancestors' options.

## LazyLoader

$lazy is Instance of LazyLoader, available for LazyRef and InViewComp.

### Methods



Name
Arguments
Description




check
-
Manually check and load itself and its children loaders which haven't loaded.

## Directives
### Lazy(v-lazy)
#### value



Type
Description




String or Object

If the value is an Object, it has the same spec as config with extra config.
If the value is a String, it will be used as `src` of config


#### Extra config for the Value of Lazy



Name
Type
Default
Description




ref
String
`null`

The name of parent view (lazy-ref component or window).

If it's not specified, it will be the window.

By now, it only supports one level of LazyRef parent.



src[2]
String
-

The resource url going to be loaded.

Only available for Lazy.



filters
Array<Function>
-

Filter the src you one by one before the element requests it.

Each filter is a function and should return the filtered url. The signiture of it should be like this:


function: String (
// Last filtered result. It will be the original src if it's the first filter.
lastResult,
// Other infomation
info: {
// The element to which the loader attaches
el,
},
) {}




retry
Integer or Function
0

If it's a number, it will be the retry amount, 0 for no retry, -1 for infinite retry.

If it's a function, it will be used to control the flow of retry.

It will pass a object parameter which has following properties:



Name
Type
Description




el
HtmlElement
The element which the loader is bound to.


src
String
The last src which is loaded.


oSrc
String
The original src you want to load.


times
Integer
N-th times retry. Begins from 0.


next
Function

Call this function and pass an parameter object to it to control the retry.

If you want to retry with the new url, you should pass it as `src` property.

If you want to stop the retry, you should pass `true` as `failed` property.




applyFilters
Function

A shortcut function to apply all filters you passed as the option. Put the url into it and you will get the filtered one.







classLoading
String

lazy-loading


Class name of loading

Only available for Lazy.



classLoaded
String

lazy-loaded


Class name of loaded

Only available for Lazy.



classErr
String

lazy-err


Class name of load error

Only available for Lazy.



classTarget
String
self

Element (real node) of class name to be changed when the load stat changes.

If it's set to `parent`, the class name of parent element will be changed.

By default, the class name of element it self will be changed.



once
Boolean
true

Remove listener after it has loaded if it is set to true.




mode
String
-

The mode the lazyload.

If it's set to 'bg', the resource will be loaded as a background image.

By default, it will be set as the "src" attribute of the element.

Only available for Lazy and LazyRef.



onLoad
Function
-

It will be called when the src is loaded successfully (after retry if it did retry).

It will pass a object parameter which has following properties:



Name
Type
Description




el
HtmlElement
The element which the loader is bound to.


src
String
The last src which is loaded.


oSrc
String
The original src you want to load.






onErr
Function
-

It will be called when the src fails to load each time.

It will pass a object parameter which has following properties:



Name
Type
Description




el
HtmlElement
The element which the loader is bound to.


src
String
The last src which is loaded.


oSrc
String
The original src you want to load.


isEnd
Boolean
Optional. It will be true when it's the failure of the last loading (after all retries if it did retry).






onReq
Function
-

It will be called when the load request begins to be sent each time.

It will pass a object parameter which has following properties:



Name
Type
Description




el
HtmlElement
The element which the loader is bound to.


src
String
The last src which is loaded.


oSrc
String
The original src you want to load.





[1]: All options should not be changed after they have initialized except for [2].

[2]: It will mark the node not loaded and load again when it's in parent view. if `once` is set to `false`.

[3]: All options will inherit its ancestors' options.

## Components
### LazyRef(lazy-ref, Experimental)



Name
Type
Default
Description




tag
String
div
The tag name of the wrapper component when it renders.


opts
Object
null
See config. And it can be used a parent option to be inherited.

### InViewComp
#### Extra config for `opts` InViewComp



Name
Type
Default
Description




onInView
Function
-

It will be called when the element is in the viewport.

It will pass wa object parameter which has following properties:



Name
Type
Description




$lazy
LazyLoader
The LazyLoader.


endCheck
Function

Call this function to stop checking whether the element is in viewport when you don't need onInView callback's firing anymore.
This function will also be called if the stat is set to `COMP_LOADED`.






[1]: All options above won't inherit its ancestors' options by now.

### LazyComp
#### Props



Name
Type
Default Value
Description




tag
String
div
The tag name of the wrapper component when it renders.


opts
Object
null

It has the same spec as config with extra config.



stat
Integer
COMP_NOT_LOAD

The status of the component which controls the slot's display.

Available constants for stat:



Name
Description




COMP_NOT_LOAD
The component is not loaded and the initial status of comopnent.


COMP_LOADING
The component is not loading.


COMP_LOADED
The component is not loaded.


COMP_ERR
The component failed to load.



Notes:


  1. Please USE THE CONSTANT VARIABLE instead of the actual value!


  2. The initial stat MUST be `COMP_NOT_LOAD` and the stat SHOULD NOT be changed
    until this component is mounted for LazyLoader's initialization.


  3. To ensure you change the status after the initialization, you should change the props "stat" in the "onInView" callback.




#### Extra config for `opts` LazyComp



Name
Type
Default
Description




classCompLoading
String

comp-stat-loading


Class name of loading

Only available for LazyComp.



classCompLoaded
String

comp-stat-loaded


Class name of loaded

Only available for LazyComp.



classCompErr
String

comp-stat-err


Class name of load error

Only available for LazyComp.



classCompNotLoad
String

comp-stat-err


Class name of load error

Only available for LazyComp.



onInView
Function
-

It will be called when the element is in the viewport.

It will pass wa object parameter which has following properties:



Name
Type
Description




$lazy
LazyLoader
The LazyLoader.


endCheck
Function

Call this function to stop checking whether the element is in viewport when you don't need onInView callback's firing anymore.
This function will also be called if the stat is set to `COMP_LOADED`.






[1]: All options above won't inherit its ancestors' options by now.

#### Slots



Name
Description




not-load
It will be shown if the prop `stat` is set to `COMP_NOT_LOAD`.


loading
It will be shown if the prop `stat` is set to `COMP_LOADING`.


err
It will be shown if the prop `stat` is set to `COMP_ERR`.


(default)
It will be shown if the prop `stat` is set to `COMP_LOADED`.

## Well, what's next?
- More abilities
- More test cases
- Performance optimization