ionic-framework: VirtualScroll Can't read property length of null

Ionic version: (check one with “x”) [ ] 1.x [ ] 2.x [x] 3.x

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Current behavior: I got Null exception at https://github.com/driftyco/ionic/blob/master/src/components/virtual-scroll/virtual-scroll.ts#L601

Expected behavior: Check for null before calling length function

Steps to reproduce:

Don’t know how to reproduce. Got it only a few times.

Related code:

insert any relevant code here

Other information:

Ionic info: (run ionic info from a terminal/cmd prompt and paste output below):

Your system information:

Cordova CLI: 6.5.0 
Ionic Framework Version: 3.1.1
Ionic CLI Version: 2.2.3
Ionic App Lib Version: 2.2.1
Ionic App Scripts Version: 1.3.6
ios-deploy version: 1.9.1 
ios-sim version: 5.0.13 
OS: macOS Sierra
Node Version: v7.3.0
Xcode version: Xcode 8.3.2 Build version 8E2002

About this issue

Original URL
State: closed
Created 7 years ago
Reactions: 8
Comments: 23 (7 by maintainers)

Most upvoted comments

Getting this issue too. Tried this:

`public hotelsarray: any[] = [];`

<ion-list [virtualScroll]="hotelsarray" approxItemHeight="50px">
      <div tappable ion-item *virtualItem="let hotel" class="item-inner-hotel" (click)="hotelClicked(hotel)">

viveksinha121 on Aug 18, 2017

same here. I get:

Cannot read property 'length' of null
    at VirtualScroll._stepDOMWrite (virtual-scroll.js:591)
    at virtual-scroll.js:551
    at dispatch (dom-controller.js:214)
    at DomController._flush (dom-controller.js:158)
    at rafCallback (dom-controller.js:147)

after I updated from 2.2.0 to 3.3.0

pantonis on Jun 3, 2017

@manucorporat I believe the source of this particular bug is a race condition between requestAnimationFrame and ngOnDestroy.

ngOnDestroy nulls out _nodes, _cells, _date, etc. at https://github.com/ionic-team/ionic/blob/master/src/components/virtual-scroll/virtual-scroll.ts#L819 but there are scheduled raf calls in renderVirtual and in _dom.read() / _dom.write() which might execute after ngOnDestroy has free’d those object properties.

Kevin-Hamilton on Oct 21, 2017

Happened few times only. Don’t know how to reproduce. Closing this as there are other important issues than this one.

aggarwalankush on Apr 30, 2017