Binary tree lofic

btree.js

// Represents the btree logic
var BTree = function() {
  var c = document.getElementById('my-canvas');
  var ctx = c.getContext('2d');
  var line = new Line();
  this.root = null;
  
  var self = this;
  
  // Getter for root
  this.getRoot = function() { return this.root; };
  
  // Adds element to the tree
  this.add = function( data) {
    // If root exists, then recursively find the place to add the new node
    if(this.root) {
      this.recursiveAddNode(this.root, null, null, data);  
    } else {
    // If not, the add the element as a root 
      this.root = this.addAndDisplayNode(200, 20, 15, ctx, data);
      return;
    } 
  };

  // Recurively traverse the tree and find the place to add the node
  this.recursiveAddNode = function(node, prevNode, coordinateCallback, data) {
    if(!node) {
      // This is either node.leftCoordinate or node.rightCoordinate
      var xy = coordinateCallback();
      var newNode = this.addAndDisplayNode(xy.cx, xy.cy, 15, ctx, data);
      line.draw(prevNode.getX(), prevNode.getY(), xy.cx, xy.cy, prevNode.getRadius(), ctx)
      return newNode; 
    } 
    else {
      if(data <= node.getData()) {
        node.left = this.recursiveAddNode(node.left, node, node.leftCoordinate, data);
      } 
      else {
        node.right = this.recursiveAddNode(node.right, node, node.rightCoordinate, data);
      }
      return node;
    }
  };
  
  // Adds the node to the tree and calls the draw function
  this.addAndDisplayNode = function(x, y, r, ctx, data) {
    var node = new Node(x, y, r, ctx, data);
    node.draw();
    return node;
  };
};