angularjs的collection-repeat用法

发布时间：2020-12-17 09:49:18 所属栏目：安全来源：网络整理

导读：http://ionicframework.com/docs/api/directive/collectionRepeat/ 首先摘录原文： collection-repeat See the Pen byIonic(@ionic) onCodePen. collection-repeat allows an app to show huge lists of items much more performantly than ng-repeat . It r

http://ionicframework.com/docs/api/directive/collectionRepeat/

首先摘录原文：

collection-repeat

See the Pen byIonic(@ionic) onCodePen.

collection-repeatallows an app to show huge lists of items much more performantly thanng-repeat.

It renders into the DOM only as many items as are currently visible.

This means that on a phone screen that can fit eight items,only the eight items matching the current scroll position will be rendered.

The Basics:

The data given to collection-repeat must be an array.
If theitem-heightanditem-widthattributes are not supplied,it will be assumed that every item in the list has the same dimensions as the first item.
Don’t use angular one-time binding (::) with collection-repeat. The scope of each item is assigned new data and re-digested as you scroll. Bindings need to update,and one-time bindings won’t.

Performance Tips:

The iOS webview has a performance bottleneck when switching out<img src>attributes. To increase performance of images on iOS,cache your images in advance and,if possible,lower the number of unique images. We’re working ona solution.

Usage

Basic Item List (codepen)

<ion-content>
  <ion-item collection-repeat="item in items">
    {{item}}
  </ion-item>
</ion-content>

Grid of Images (<img "photo in photos" item-width="33%" item-height="200px" ng-src="{{photo.url}}"> </ion-content>

Horizontal Scroller,Dynamic Item Width (<h2>Available Kittens:</h2> <ion-scroll direction="x" class="available-scroller"> <div "photo" "photo in main.photos" "250" "photo.width + 30"> "{{photo.src}}"</div> </ion-scroll> </ion-content>

API

Attr	Type	Details
collection-repeat	`expression`	The expression indicating how to enumerate a collection,of the format`variable in expression`– where variable is the user defined loop variable and`expression`is a scope expression giving the collection to enumerate. For example:`album in artist.albums`or`album in artist.albums \| orderBy:'name'`.
item-width (optional)	The width of the repeated element. The expression must return a number (pixels) or a percentage. Defaults to the width of the first item in the list. (previously named collection-item-width)
item-height (optional)	The height of the repeated element. The expression must return a number (pixels) or a percentage. Defaults to the height of the first item in the list. (previously named collection-item-height)
item-render-buffer (optional)	number	The number of items to load before and after the visible items in the list. Default 3. Tip: set this higher if you have lots of images to preload,but don't set it too high or you'll see performance loss.
force-refresh-images (optional)	boolean	Force images to refresh as you scroll. This fixes a problem where,when an element is interchanged as scrolling,its image will still have the old src while the new src loads. Setting this to true comes with a small performance loss.

（编辑：李大同）

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