TypeError: undefined is not an object (evaluating 'next.length')

[flatsiedatsie]

Describe the issue

When javascript code uses backticks, the code can disappear. I've been trying to narrow down what causes it. I believe it has something to do with long strings in between backticks, or with code being in between two long backtick blocks.

TO REPRODUCE Paste data from a table into a javascript variable that uses backquotes, so that the backquote variable becomes taller than the textarea.

1. Open https://codemirror.net/
2. Paste the below code into the example codemirror instance, replacing the old example code.
3. Expand the area in between the first two backticks. You can try entering a couple of newlines, but for the best effect select some contents of a long html table and copy that into the variable (at 'paste over me'. The important thing is to make the content longer than the height of the textarea, so it overflows.
4. Scroll up and down rapidly a few times.
5. notice strange behaviour, or even a fully white editor. Clicking on it can resolve it, using arror keys can make it worse.

Copy this:

// codemirror issue when scrolling over long backtick variables
// let test = "a normal variable";    
let test = `    

paste over me

`

async function init_tf() {

    console.log("BEAUTY WORKER: LOADING BEAUTY TENSORFLOW MODEL");
    const LOCAL_MODEL_PATH = './models/beauty.json';
    //const HOSTED_MODEL_PATH = './models/beauty.json';

    //let model;
    try {
        model = await tf.loadLayersModel(LOCAL_MODEL_PATH);
        //window.model.summary();
        //beauty_detector_ready = true;
        postMessage({'loaded':'beauty'});

    } catch (err) {
        console.log("failed to load beauty scoring model:", err);
        //alert("failed to load beauty scoring model");
        document.getElementById('debug-log').innerHTML = "Error, beauty worker: failed to load model";

    }

}

init_tf();

onmessage = function(incoming) {
    //console.log('Message received from main script');

    var return_message = null;

    if (!model) {
        console.log("* no model loaded")
        return null;
    }
    else{
        //console.log("onmessage in beauty worker. Model was loaded. incoming data:");
        //console.log(incoming)

        /*
        result = incoming.data;
        console.log("incoming result object in web worker:");
        console.log(result);
        console.log(result.descriptor);
        */
        if( 'data' in incoming ){
            //console.log("data in incoming beauty prediction");
            try{

                if( incoming.data.length == 128 ){
                    //console.log("beauty worker: incoming data was 128 long");
                    var vector_array = [];
                    for (var i = 0; i < incoming.data.length; i++) {
                        vector_array.push( incoming.data[i] );
                    }

                    const shape = [1,128];

                    // Run the normalized array through the model to get a prediction
                    let result = tf.tidy( () => {
                        //console.log("predingting BMI now..");
                        //return model.predict( tf.stack( [ tf.tensor1d( normalized ) ] ) );
                        var a = tf.tensor(vector_array,shape,'float32');

                        const prediction = model.predict( a );
                        return_message = prediction.dataSync();
                    });

                    //prediction.dispose();
                    //let prediction = await result.data();
                    //console.log("result.data() = " + result.data());
                    //let prediction = await result.data();
                    //result.dispose();

                    //console.log("beauty worker: prediction: " + return_message);
                }
                else{
                    console.log("beauty worker: incoming data should be array of 128 floats (face fingerprint)");
                }

            }
            catch(e){
                console.log("error: beauty worker: " + e);
            }
        }       
        else{
            console.log("beauty worker: no data in incoming message");
        }
    }

    //var workerResult = 'Result: ' + (incoming.data[0] * incoming.data[1]);
    //console.log('Posting message back to main script');
    postMessage(return_message);
}

async function init_tf() {

    console.log("BEAUTY WORKER: LOADING BEAUTY TENSORFLOW MODEL");
    const LOCAL_MODEL_PATH = './models/beauty.json';
    //const HOSTED_MODEL_PATH = './models/beauty.json';

    //let model;
    try {
        model = await tf.loadLayersModel(LOCAL_MODEL_PATH);
        //window.model.summary();
        //beauty_detector_ready = true;
        postMessage({'loaded':'beauty'});

    } catch (err) {
        console.log("failed to load beauty scoring model:", err);
        //alert("failed to load beauty scoring model");
        document.getElementById('debug-log').innerHTML = "Error, beauty worker: failed to load model";

    }

}

init_tf();

onmessage = function(incoming) {
    //console.log('Message received from main script');

    var return_message = null;

    if (!model) {
        console.log("* no model loaded")
        return null;
    }
    else{
        //console.log("onmessage in beauty worker. Model was loaded. incoming data:");
        //console.log(incoming)

        /*
        result = incoming.data;
        console.log("incoming result object in web worker:");
        console.log(result);
        console.log(result.descriptor);
        */
        if( 'data' in incoming ){
            //console.log("data in incoming beauty prediction");
            try{

                if( incoming.data.length == 128 ){
                    //console.log("beauty worker: incoming data was 128 long");
                    var vector_array = [];
                    for (var i = 0; i < incoming.data.length; i++) {
                        vector_array.push( incoming.data[i] );
                    }

                    const shape = [1,128];

                    // Run the normalized array through the model to get a prediction
                    let result = tf.tidy( () => {
                        //console.log("predingting BMI now..");
                        //return model.predict( tf.stack( [ tf.tensor1d( normalized ) ] ) );
                        var a = tf.tensor(vector_array,shape,'float32');

                        const prediction = model.predict( a );
                        return_message = prediction.dataSync();
                    });

                    //prediction.dispose();
                    //let prediction = await result.data();
                    //console.log("result.data() = " + result.data());
                    //let prediction = await result.data();
                    //result.dispose();

                    //console.log("beauty worker: prediction: " + return_message);
                }
                else{
                    console.log("beauty worker: incoming data should be array of 128 floats (face fingerprint)");
                }

            }
            catch(e){
                console.log("error: beauty worker: " + e);
            }
        }       
        else{
            console.log("beauty worker: no data in incoming message");
        }
    }

    //var workerResult = 'Result: ' + (incoming.data[0] * incoming.data[1]);
    //console.log('Posting message back to main script');
    postMessage(return_message);
}

let old_source = `
English Wikipedia   English Wikipedia   English Latn    en  120,580 15 January 2001 
Wikipedia logo showing "Wikipedia: The Free Encyclopedia" in English
German Wikipedia    Deutschsprachige Wikipedia  German  Latn    de  17,398  16 March 2001   
Wikipedia logo showing "Wikipedia: The Free Encyclopedia" in German
French Wikipedia    Wikipédia en français   French  Latn    fr  17,346  23 March 2001   
Wikipedia logo showing "Wikipedia: The Free Encyclopedia" in French
Spanish Wikipedia   Wikipedia en español    Spanish Latn    es  13,965  20 May 2001 
Wikipedia logo showing "Wikipedia: The Free Encyclopedia" in Spanish
Japanese Wikipedia  ウィキペディア日本語版
(Wikipedia nihongo-ban) Japanese    Jpan    ja  13,879  20 May 2001 
Wikipedia logo showing "Wikipedia: The Free Encyclopedia" in Japanese
Russian Wikipedia   Русская Википедия
(Russkaya Vikipediya)   Russian Cyrl    ru  9,795   20 May 2001 
Wikipedia logo showing "Wikipedia: The Free Encyclopedia" in Russian
Portuguese Wikipedia    Wikipédia em português  Portuguese  Latn    pt  8,447   11 May 2001 
Wikipedia logo showing "Wikipedia: The Free Encyclopedia" in Portuguese
Chinese Wikipedia   Traditional Chinese: 中文維基百科,
simplified Chinese: 中文维基百科
(pinyin: Zhōngwén wéijī bǎikē)  Chinese
(written vernacular Chinese)    Hans/Hant   zh  7,846   24 October 2002 
Wikipedia logo showing "Wikipedia: The Free Encyclopedia" in Chinese
Italian Wikipedia   Wikipedia in italiano   Italian Latn    it  7,718   11 May 2001 
Wikipedia logo showing "Wikipedia: The Free Encyclopedia" in Italian
Persian Wikipedia   ویکی‌پدیای فارسی
(Vikipediyâ fārsi)  Persian Arab    fa  5,247   19 December 2003    
Wikipedia logo showing "Wikipedia: The Free Encyclopedia" in Persian
Polish Wikipedia    Polskojęzyczna Wikipedia    Polish  Latn    pl  4,348   26 June 2001    
Wikipedia logo showing "Wikipedia: The Free Encyclopedia" in Polish
Arabic Wikipedia    ويكيبيديا العربية
(Wīkībīdiyā al-ʿarabiyya)   Arabic  Arab    ar  4,125   8 July 2003 
Wikipedia logo showing "Wikipedia: The Free Encyclopedia" in Arabic
Dutch Wikipedia Nederlandstalige Wikipedia  Dutch   Latn    nl  3,751   19 June 2001    
Wikipedia logo showing "Wikipedia: The Free Encyclopedia" in Dutch
Ukrainian Wikipedia Українська Вікіпедія
(Ukrayinsʹka Vikipediya)    Ukrainian   Cyrl    uk  3,497   30 January 2004 
Wikipedia logo showing "Wikipedia: The Free Encyclopedia" in Ukrainian
Hebrew Wikipedia    ויקיפדיה העברית
(Vikipedya ha-ivrit)    Hebrew  Hebr    he  3,135   8 July 2003 
Wikipedia logo showing "Wikipedia: The Free Encyclopedia" in Hebrew
Indonesian Wikipedia    Wikipedia bahasa Indonesia  Indonesian  Latn    id  3,069   30 March 2003   
Wikipedia logo showing "Wikipedia: The Free Encyclopedia" in Indonesian
Turkish Wikipedia   Türkçe Vikipedi Turkish Latn    tr  2,715   5 December 2002 
Wikipedia logo showing "Wikipedia: The Free Encyclopedia" in Turkish
Swedish Wikipedia   Svenskspråkiga Wikipedia    Swedish Latn    sv  2,285   23 May 2001 
Wikipedia logo showing "Wikipedia: The Free Encyclopedia" in Swedish
Czech Wikipedia Česká Wikipedie Czech   Latn    cs  2,041   3 May 2002  
Wikipedia logo showing "Wikipedia: The Free Encyclopedia" in Czech
Vietnamese Wikipedia    Wikipedia tiếng Việt    Vietnamese  Latn    vi  1,918   November 2002 (unknown day) 
Wikipedia logo showing "Wikipedia: The Free Encyclopedia" in Vietnamese
Korean Wikipedia    한국어 위키백과
(Han-gugeo wikibaekgwa) Korean  Hang    ko  1,805   11 October 2002 
Wikipedia logo showing "Wikipedia: The Free Encyclopedia" in Korean
Finnish Wikipedia   Suomenkielinen Wikipedia    Finnish Latn    fi  1,576   21 February 2002    
Wikipedia logo showing "Wikipedia: The Free Encyclopedia" in Finnish
Hungarian Wikipedia Magyar Wikipédia    Hungarian   Latn    hu  1,536   8 July 2003 
Wikipedia logo showing "Wikipedia: The Free Encyclopedia" in Hungarian
Simple English Wikipedia    Simple English Wikipedia    Simple English  Latn    simple  1,375   18 September 2001   
Wikipedia logo showing "Simple English Wikipedia" in English
Hindi Wikipedia हिन्दी विकिपीडिया
(Hindī vikipīḍiyā)  Hindi   Deva    hi  1,207   11 July 2003
`

Browser and platform

MacOS, Both Safari and Brave are affected

Reproduction link

No response

[marijnh]

Attached patch should help. In the end this had nothing to do with template strings or pasting, but your reproduction instructions helped me narrow it down.

[flatsiedatsie]

Glad I could help! Thanks for the patch, I'll try to implement it. Loving codemirror so far! I only wish the documentation sometimes had examples.