Autocomplete does not trigger in parentheses


I implemented Autocompletion in my editor and it is working fine.
But if I try to trigger it within parentheses, i.e.


the autocompletion is not triggered (it should show “mouse”). Outside the brackets it works.

I think I found the problem in the matchBefore-method in codemirror/autocomplete:

matchBefore(expr) {

        let line = this.state.doc.lineAt(this.pos);
        let start = Math.max(line.from, this.pos - 250);
        let str = line.text.slice(start - line.from, this.pos - line.from);
        let found =, false));
        return found < 0 ? null : { from: start + found, to: this.pos, text: str.slice(found) };

This yields the whole string ‘drawCircle(mou’ and therefore the autocompletion for ‘mouse’ is not triggered.

I think there should be an option to configure the autocomplete package to define delimiter-characters such that you can specify to break at such characters like ‘(’ or ‘,’. Another solution would be to set the hard-coded 250 to 0.

You can find my editor here. Just type ‘mou’ in a free line and you will get the hints. If you type ‘drawCircle(mou’ there won’t be a completion.

What regular expression are you passing to matchBefore?

I do not pass anything, the package does this on its own.
I think, this (showing no hints if caret is in brackets) is standard behaviour of CM 6, isn’t it?

How did you set up autocompletion, then?

Thanks in advance. This should be the relevant code:

this.language=new Compartment();
      let editor=new EditorView({
        state: EditorState.create({
          doc: "",
          extensions: [
            indentUnit.of("  "),
            EditorView.updateListener.of((v) => {
              if(timer) clearTimeout(timer);
              timer = setTimeout(() => {
                if (changed) {
              }, 500 );
        parent: this.$refs.editor

So I use the autocompletion out of the box.

The standard completion provided by javascript() will never complete mouse, so I think you’re misunderstanding something.

Okay, you’re right. I also take the snippets from @codemirror/lang-javascript and remove all existing snippets. After that I add new snippets a ka

snippets.push(autocomplete.snippetCompletion("Math.pow(${basis},${exp})", {
    label: "Math.pow",
    info: "Berechnet basis hoch exp.",
    type: "function"

As I said, the hints are displayed outside of brackets, but not inside.

Thank you very much for your quick answers by the way. I really appreciate that!

JavaScript autocompletion works fine for me inside square and curly brackets.

Okay, now it works after reading your autocompletion example.
Thank you very much!