Uncaught TypeError: Cannot set property '0' of undefined

[tqlihuiqi]

execute vi / vim command throw exception

error:
Uncaught TypeError: Cannot set property '0' of undefined

debug:
Serial port requested application keypad.

code:
<script src="/static/plugins/xterm/src/xterm.js"></script>

    var currentWs = new ReconnectingWebSocket('ws://{{ wsServer }}/ws/terminal/current');
    currentWs.onopen =  function(event) {
        var xterm = new Terminal({
            geometry: [98, 26],
            debug: true
        });
        xterm.open(document.getElementById('currentRecord'));
        currentWs.onmessage = function(event) {
            xterm.write(event.data);
        }; 
    }

[akalipetis]

Hello @tqlihuiqi - thanks for reporting.

Are you testing on the latest master branch? Also, in which browser you're testing?
I just tried running vi/vim on the Xterm demo but could not reproduce this on Chrome/Firefox on OSX.

[tqlihuiqi]

Hi, @akalipetis

I use the latest master branch on Chrome/Firefox on OSX.

I've already resolve this issue.

code:

var currentWs = new ReconnectingWebSocket('ws://{{ wsServer }}/ws/terminal/current');
currentWs.onopen =  function(event) {
    var xterm = new Terminal({
        geometry: [98, 26],
        debug: true
    });
    xterm.open(document.getElementById('currentRecord'));
    currentWs.onmessage = function(event) {
        if(!xterm.write(event.data)){
            xterm.write('');
        }
    }; 
}

[jerch]

@tqlihuiqi Could you provide more info about what you did, the error (with stacktrace?) and what exactly fixed the problem? The

        if(!xterm.write(event.data)){
            xterm.write('');
        }

doesnt look like a real solution to me - you still execute xterm.write(event.data) and evaluate a nonexistent return value (the if condition will always be true).

Atm your description is somewhat cryptic and not reproducable with the spare info.

[tqlihuiqi]

@jerch

I have written a with the function of audit SSH client，I want to send the output file via a browser display, So I use the WEBSOCKET receives the message, and then through the XTERM to display a message to the page. At that time when I was in terminal input VI command, raised exception.

I try to write VI command returns a message on the console:

console.log(event.data)

terminal:524 v
terminal:524 i
terminal:524 

terminal:524 �[?1h�=
terminal:524 �[1;30r�[m�[m�[0m�[H�[J�[2;1H�[1m~

25terminal:524 ~

XTERM throw an exception

Terminal.write  @   xterm.js:1603
currentWs.onmessage @   terminal:525
(anonymous function)    @   reconnecting-websocket.js:182
ws.onmessage    @   reconnecting-websocket.js:282

xterm.js:1603
this.lines[this.y + this.ybase][this.x] = [this.curAttr, ch, ch_width];

So I judge xterm.write(event.data) back to write page success, throw an exception when I would write a null character

[jerch]

Looks like this.lines or this.lines[this.y + this.ybase] is undefined. You'd have to inspect both to see what is wrong here, either with printf-debugging (console.log) or with a breakpoint at xterm.js:1603.

I guess your xterm geometry is not in sync with the pty, since vi is trying to set the y scroll margins to 0 and 29 ([1;30r in your second vi output line).

[parisk]

@tqlihuiqi opening vim in the demo page does not throw any errors or exceptions. When I explicitly write the NUL byte character to the terminal with term.write('\0') still no error or exception is being raised.

Could you please update to the latest version of the master branch and provide us with the following information:

1. On what OS does the back-end PTY of your xterm.js instance run?
2. What is the exact command that you run
3. A screenshot of your app with the Chrome DevTools open in the Console tab

This way we will be able to approach this problem better and find out why this happens.

[JasinYip]

I have the same problem on our project. Opening vim does not throw any errors before I press some keys like j.

And I could use :q to exit vim but after that, the last line of the terminal will change its color to purple. That's really weird...

[LucianBuzzo]

I've been able to replicate this issue by setting a scroll region to a bottom value that is higher then the number of rows, then printing a lot of new lines to the screen.
You can do this using the following simple bash script:

printf "\033[1;300r"
grep -Rl ' ' .

I'll submit a PR with a fix.

[parisk]

Closed in #514.

[tht13]

I am on the latest version of xterm and am receiving this error again. Has something gone in recently which could have brought this bug back? It always seems to fail on row 24. While my terminal is configured with 7 rows. I inspected the this._terminal.lines element and there are only 23 rows but "24.2" does exist.

[Tyriar]

@tht13 can you get the stack and try find the line it's failing on? I added some defensive checks to protect against at least one case of this. It might be a different regression (I haven't seen any reports though on 2.6).

[tht13]

It is failing on InputHandler.ts:86

Stacktrace:

InputHandler.ts:86 Uncaught TypeError: Cannot set property '0' of undefined
    at InputHandler.addChar (InputHandler.ts:86)
    at Parser.parse (Parser.ts:221)
    at Terminal.innerWrite (xterm.js:1296)
    at xterm.js:1275
InputHandler.addChar @ InputHandler.ts:86
Parser.parse @ Parser.ts:221
Terminal.innerWrite @ xterm.js:1296
(anonymous) @ xterm.js:1275
setTimeout (async)
Terminal.write @ xterm.js:1274
log @ terminal.tsx:25

[tht13]

I've debugged a bit further and the problem seems to come from calling a resize while writing to the terminal. The async nature of the write seems to cause some issue. I'll add a wait on the resize event to my code, that should fix it.

[tht13]

Unfortunately waiting on the resize event didn't help, I thought I solved the issue by delaying the resize through a timeout but it seems that any write to the terminal after the resize causes it to fail, even if it is minute later.

Here is some code which should reproduce the issue (without the timeout):

const term = new xterm();
term.open(document.getElementById("container"));
term.resize(cols, rows);
for (let i=0;i<30;i++) term.writeln(i.toString());

[Tyriar]

Thanks @tht13, I created #661 to follow this up, hopefully in the next version.