undefined is not an object (evaluating 'this._data[this._data.length-1].push')

[lathonez]

Hey,

I'm just raising this for your visibility / in case you have any ideas. I don't have a repro and am not expecting you to be able to do anything to solve this.

We're getting this error thrown on one of our production apps. We have lots of apps running out there and only one has ever had this issue, which suggests to me it might be device related.

The error

undefined is not an object (evaluating 'this._data[this._data.length-1].push')

Is being thrown from here:

https://github.com/szimek/signature_pad/blob/master/src/signature_pad.js#L173-L178

That's pretty much all the info I have. The client using the app hasn't reported anything to us from a behaviour perspective.

Other info:

• Ionic 3 / Angular 4 app deployed via the AppStore
• iPad Model: iPad6,11
• UA: UA: Mozilla/5.0 (iPad; CPU OS 11_0_1 like Mac OS X) AppleWebKit/604.1.38 (KHTML, like Gecko) Mobile/15A402

I am tracking the issue and will update you if I get further information.

Thanks for all your hard work on this repo,

Stephen

[lathonez]

Just seen again on another instance of the app:

• iOS 11.2.5
• iPad6,11

[stefankunze]

I also can see that Issue on Chrome Mobile v.56.0.2924/64.0.3282 on Android v.7.0
Seems to be within the _strokeUpdate function

[timbru31]

I'm joining the club with the error messages:
TypeError: Cannot read property 'push' of undefined and TypeError: Cannot read property 'length' of undefined

Our tracking said it's a Samsung SM-T5851 with Chrome 64.0.01 and running Android 7.0.01

---

Minified stack trace:

Cannot read property 'push' of undefined
at i._strokeUpdate (scripts.09258a303eed71dcb9ac.bundle.js:1)
at i._strokeMoveUpdate (scripts.09258a303eed71dcb9ac.bundle.js:1)
at HTMLCanvasElement._handleTouchMove (scripts.09258a303eed71dcb9ac.bundle.js:1)
at e.invokeTask (polyfills.395920b077ebea14c462.bundle.js:1)
at Object.onInvokeTask (main.4f4970c93c661f275c5d.bundle.js:1)
at e.invokeTask (polyfills.395920b077ebea14c462.bundle.js:1)
at t.runTask (polyfills.395920b077ebea14c462.bundle.js:1)
at t.invokeTask [as invoke] (polyfills.395920b077ebea14c462.bundle.js:1)
at _ (polyfills.395920b077ebea14c462.bundle.js:1)
at HTMLCanvasElement.m (polyfills.395920b077ebea14c462.bundle.js:1)

[bbialas]

+1

[sp53519]

+1

[rafaelgrilli92]

Same issue:
Message | undefined is not an object (evaluating 'this._data[this._data.length-1].push')
Failed method | _strokeUpdate |  
Device model | iPhone |  
Operating system | iOS 12.0 |  
Browser version | Mobile Safari 12.0

Also this straight after the error above:
Message | undefined is not an object (evaluating 'a.length') |
Failed method | _strokeEnd |  
Device model | iPhone |  
Operating system | iOS 12.0 |  
Browser version | Mobile Safari 12.0

And the issue has been open since January and got no answers =/

[jmeinke]

Maybe the TypeScript rewrite (-> version 3) from @szimek will remove this error. We also have got a report about it via Sentry for Mobile Safari 12.0 on iPad with iOS 12.1.1. We are currently using Signature Pad version 2.3.2.

[busiweb]

I think I've found the solution: Add the following line inside the o.prototype.clear function (above everything else):
this._data = [];

[rafaelgrilli92]

@busiweb did it work? If so, do a pull request with the fix, plz

[dphrag]

Saw this reported on a Safari 12.1 / iOS 12.2 device :(

[JosNun]

Also experiencing this issue. iPad with iOS 12.2

[lewisloofis]

Also experiencing this issue, Samsung SM-J730G with Android 7.0. Any update on this?

[webfletch]

Also experiencing this issue on iPhone 11 Pro with iOS 13.4.1. It doesn't seem to cause a problem for the end-user but now that my App has error logging it is rather annoying receiving alerts about this.

[JosNun]

@UziTech As far as I'm aware, this issue hasn't been resolved. I'm assuming it's been closed to clean up issues that are stale?

[UziTech]

If this is still an issue you can open another issue with more information. As far as I know this issue has been resolved in the latest beta release.

[JosNun]

Ah, my bad. I looked at the tags and didn't see a beta 4 tag. I didn't realize that beta 4 had only been pushed to NPM.

[capc0]

can someone confirm that the issue is fixed?

the changelog https://github.com/szimek/signature_pad/blob/master/CHANGELOG.md#300-beta4 only references another issue #480 instead of this one.

[agilgur5]

Looking at #481, I believe it should have fixed this as well. The early return for the race condition there is in the same method as this issue. So, if I understand correctly, if this._data.length === 0 this line won't be hit either and so this error shouldn't occur.

That is of course only if the root cause for this error is the same race condition (that causes this to evaluate to a buggy this.data[-1].push)