Q:

How to add key press listener for IText objects in FabricJS?

I currently have this code

fabric.IText.prototype.keysMap[13] = 'onEnterKeyPress';
fabric.IText.prototype.onEnterKeyPress = (e) => {
  console.log('onEnterKeyPress', e);
  // this.insertChars(e);
  // fabric.IText.insertChars(e);
  // return true;
  // return e;
};
  
let canvas = new fabric.Canvas('canvas', {
  preserveObjectStacking: true,
  width: 980,
  height: 600
});

let itext = new fabric.IText(
  'Edit this text',
  {
    editable: true,
    left: 100,
    top: 100,
    fontSize: 24
  }
);

canvas.add(itext);
canvas.requestRenderAll();
<html>
  <body>
    <canvas id="canvas"></canvas>
    <script src="https://cdnjs.cloudflare.com/ajax/libs/fabric.js/2.3.4/fabric.min.js"></script>
  </body>
</html>

The issue is, once I attached the key press listener, if I hit enter key, it does fire my function callback but it won't add the carriage return character in the text.
If I remove my key press listener, it does go back to normal, that is adding the carriage return character on enter key press.
It seems I have to manually add the carriage return when I attached a key press listener? Not sure how to do it tho.
Thanks in advance.
BTW I'm using latest of FabricJS 2.3.4

A:

You can override onKeyDown, then call original method.
DEMO*

fabric.IText.prototype.onKeyDown = (function(onKeyDown) {
  return function(e) {
    if (e.keyCode == 13)
      console.log('enter key');
    onKeyDown.call(this, e);
  }
})(fabric.IText.prototype.onKeyDown)

let canvas = new fabric.Canvas('canvas', {
  preserveObjectStacking: true,
  width: 980,
  height: 600
});

let itext = new fabric.IText(
  'Edit this text', {
    editable: true,
    left: 100,
    top: 100,
    fontSize: 24
  }
);

canvas.add(itext);
canvas.requestRenderAll();
<html>
  <body>
    <canvas id="canvas"></canvas>
    <script src="https://cdnjs.cloudflare.com/ajax/libs/fabric.js/2.3.4/fabric.js"></script>
  </body>
</html>

