Set certain regions of an Ace editor to readOnly

app.coffee

event = require('pilot/event')
Anchor = require('ace/anchor').Anchor
doc = ace_editor.session.getDocument()

editablePositions = [[1, 0, 2, 0]] # allow editong only the second row
jQuery.each editable, (index, row) ->
  editablePositions.push [new Anchor(doc, row[0], row[1]), new Anchor(doc, row[2], row[3])]

Range = require('ace/range').Range

event.addListener(jQuery('#ace textarea')[0], 'keydown', (e) ->
  # console.log e.type, e.charCode, e.keyCode, e
  position = ace_editor.getCursorPosition()
  
  setReadOnly = false
  
  jQuery.each editablePositions, (index, editableAnchors) ->
    editableRange = Range.fromPoints editableAnchors[0].getPosition(), editableAnchors[1].getPosition()
    setReadOnly = !editableRange.contains(position.row, position.column)
  
  ace_editor.setReadOnly setReadOnly
)

What is "require('pilot/event')" file

This code snippet will prevent the user from editing the first or last line of the editor:

editor.commands.on("exec", function(e) { 
  var rowCol = editor.selection.getCursor();
  if ((rowCol.row == 0) || ((rowCol.row + 1) == editor.session.getLength())) {
    e.preventDefault();
    e.stopPropagation();
  }
});

https://jsfiddle.net/tripflex/y0huvc1b/

Source:
https://groups.google.com/forum/#!topic/ace-discuss/yffGsSG7GSA

thanks!

It doesn't work if the user selects many lines, then deletes. (cursor is not in the first or the last line)

This code snippet will prevent the user from editing the first or last line of the editor:

editor.commands.on("exec", function(e) { 
  var rowCol = editor.selection.getCursor();
  if ((rowCol.row == 0) || ((rowCol.row + 1) == editor.session.getLength())) {
    e.preventDefault();
    e.stopPropagation();
  }
});

https://jsfiddle.net/tripflex/y0huvc1b/

Source: https://groups.google.com/forum/#!topic/ace-discuss/yffGsSG7GSA

@tripflex Hey , In this e.preventDefault will not throw error?