Some ideas on improvement of autocompletion

[shanhaiying]

Autocompletion for {},[],() in latex envs invalidate those autocompletion of codemirror. So {},[],() should be deleted from the variable: array_completion. I add smartbackspace for "$$":

//smart delete for $.
            if (event.key == "Backspace") {
                    var ran = {
                        line: cur.line,
                        ch: cur.ch - 1
                    }
                    var ran2 = {
                        line: cur.line,
                        ch: cur.ch - 2
                    }

                    var ran3 = {
                        line: cur.line,
                        ch: cur.ch + 1
                    }
                    var pre1ch = editor.getRange(ran, cur);
                    var pre2ch = editor.getRange(ran2, cur);                    
                    var pos1ch = editor.getRange(cur,ran3);

                    if(pre1ch == "$"){
                        if (pos1ch == "$") {
                            editor.replaceRange("", cur, ran3);
                            return true
                        }

                        if (pre2ch == "$$"||pre2ch == "\\$") {
                              var ran0 = {
                                    line: cur.line,
                                    ch: cur.ch - 1
                                }
                            editor.replaceRange("", ran0, cur);
                            return true
                        }

                    }
          }

I also add an keymap for autocompletion for environments:

cmds[map["Ctrl-L E"] = "Environment"] = function(cm) 
{  
    var cur
    if(cm.somethingSelected()){
            var env=cm.getSelection() 
            cm.replaceSelection("")
            }
        else{
            cur=cm.getCursor()
            cm.moveH(-1, "char") 
            var word = cm.findWordAt(cm.getCursor()) 
            cm.moveH(1, "char")
            var env=cm.getRange(word.anchor, word.head)
            env=env.trim()
            if(env !=""){
            cm.setSelection(word.anchor,word.head)
            }
        }
        cm.replaceSelection("\\begin{"+env+"}\n\n\\end{"+env+"}")
    if(env !=""){   
    cm.moveV(-1, "line")
    }
    else{
    var line=cur.line
    var curpos=cur.ch
                  var c=[
                  {anchor:{line:line,ch:curpos+7},head:{line:line,ch:curpos+7}},
                  {anchor:{line:line+2,ch:5},head:{line:line+2,ch:5}}
                  ]
                cm.setSelections(c)
    }
    return false;
};

I tyr to add autocompletion for latex command for \alpha, \beta,...., as the way in: https://ejgallego.github.io/CodeMirror-TeX-input/demo/tex-input.html But I can not make it work by desired way. I am not familiar with javascript in jupyter notebook.

Can you give me some help? Thanks!