Cannot read properties of undefined (reading 'length')

[whereyougo]

environment:

vue3, vue-cli ^4.5
"codemirror": "^5.63.3"
chrome browser 93.0.4577.82（x86_64)

problem:

switch cm from small window to fullscreen, then click any where of the fullscreen invoke exception message in the browser console tab:
codemirror.js?56b3:2354 Uncaught TypeError: Cannot read properties of undefined (reading 'length')
at mapFromLineView (codemirror.js?56b3:2354)
at prepareMeasureForLine (codemirror.js?56b3:2407)
at cursorCoords (codemirror.js?56b3:2658)
at scrollPosIntoView (codemirror.js?56b3:3460)
at endOperation_finish (codemirror.js?56b3:3917)
at endOperations (codemirror.js?56b3:3836)
at eval (codemirror.js?56b3:3819)
at finishOperation (codemirror.js?56b3:2058)
at endOperation (codemirror.js?56b3:3816)
at HTMLDivElement.eval (codemirror.js?56b3:3953)

the vue function to switch cm view mode is:
fullScreen(type){
cm.setOption("fullScreen", !cm.getOption("fullScreen"));
}

i have debug the code where exception throws,
function mapFromLineView(lineView, line, lineN) { if (lineView.line == line) { return {map: lineView.measure.map, cache: lineView.measure.cache} } for (var i = 0; i < lineView.rest.length; i++) { if (lineView.rest[i] == line) { return {map: lineView.measure.maps[i], cache: lineView.measure.caches[i]} } } for (var i$1 = 0; i$1 < lineView.rest.length; i$1++) { if (lineNo(lineView.rest[i$1]) > lineN) { return {map: lineView.measure.maps[i$1], cache: lineView.measure.caches[i$1], before: true} } } }
when click on the fullscreen cm the method mapFromLineView will execute second for loop(first if not return true),the lineView.rest is undefine, so invoke "Uncaught TypeError: Cannot read properties of undefined (reading 'length')" exception

every click anywhere will throw the same exception

[marijnh]

Does 367b5e7 help for this?

[whereyougo]

thanks for your attention,the fix 367b5e7 resolved the "undefined (reading 'length') " problem,but i get a new exception:
Uncaught TypeError: Cannot read properties of undefined (reading 'map')
at prepareMeasureForLine (codemirror.js?56b3:2412)
at cursorCoords (codemirror.js?56b3:2660)
at scrollPosIntoView (codemirror.js?56b3:3462)
at endOperation_finish (codemirror.js?56b3:3919)
at endOperations (codemirror.js?56b3:3838)
at eval (codemirror.js?56b3:3821)
at finishOperation (codemirror.js?56b3:2058)
at endOperation (codemirror.js?56b3:3818)
at HTMLDivElement.eval (codemirror.js?56b3:3955)

method mapFromLineView not throw "undefined (reading 'length')" exception,but return undefined result then invoke another "undefined (reading 'map')" exception

the step i used to test 367b5e7 :
1.git checkout 367b5e7
2.fix "version" from "5.63.3" to "5.63.4" of package.json
3.npm pack this cmd will generate a file named codemirror-5.63.4.tgz
4.in my test projetct "codemirror_demo" fix version of package.json to "codemirror": "^5.63.4" then install this npm package by npm install /xx/xx/codemirror-5.63.4.tgz
5.use "npm run serve" to start my codemirror_demo project, view FullScreen page by http://localhost:8080, click fullscreen button then click the area of cm,chrome chonsole will throw new exception undefined (reading 'map') ,illustrate the fixed code has been executed but not resolved problem

i have try use codemirror without vue and all works fine(can be tested by codemirror_demo project with http://localhost:8080/test.html), but it not ok when use vue. There is another problem when i set initial content for cm then click the area of cm will throw same exception of undefined (reading 'length') but with difference run stack :
Uncaught TypeError: Cannot read properties of undefined (reading 'length')
at mapFromLineView (codemirror.js?56b3:2354)
at prepareMeasureForLine (codemirror.js?56b3:2407)
at coordsCharInner (codemirror.js?56b3:2754)
at coordsChar (codemirror.js?56b3:2722)
at posFromMouse (codemirror.js?56b3:2973)
at CodeMirror.onMouseDown (codemirror.js?56b3:7343)
at HTMLDivElement.eval (codemirror.js?56b3:3952)

[marijnh]

On closer look, this should never happen, event without the the patch I added. I don't know a lot about vue, but I do know that it adds invasive proxies around objects in some situations. Are you using your CodeMirror instance in such a way that vue will mess with it? That is not supported by this library.

[whereyougo]

All right,I will use codemirror without vue.
I forgot paste the codemirror_demo project url last reply.I post it here easy for you test if you're interested.

[losetime]

I also encountered this problem using vue3. It was indeed caused by the intrusion of object proxy. Don't use ref or reactive. You can solve this problem by directly defining an instance.

[whereyougo]

thanks for your feedback. Can you introduce more detail of the way "directly defining an instance" @losetime

[losetime]

define variables directly, do not use responsive, such as:
let instances = null const initEditor = () => { instances = CodeMirror.fromTextArea(textarea, options}) }
This is currently feasible

[whereyougo]

Thank you.It works. I have add this demo to the codemirror_demo project

[lennokiki]

let instances = null const initEditor = () => { instances = CodeMirror.fromTextArea(textarea, options}) }

Yes, you are right. Should not using vue3 ref to define codeMirror editor instance. God! it's bothering me two days, thank you.