improving BSTs in ECMAScript

Let's add the ability to instantiate the BST with any number of nodes we want.
      "use strict";

      const BinarySearchTree = function(n) {

      this.root = { n: n.shift() };

      this.insert = (n, current = this.root) => {

      if (n === current.n) { throw "NotUnique"; }

      const nextBranch = n < current.n ? 'left' : 'right';

			     if (current[nextBranch]) {
			     this.insert(n, current[nextBranch]);
			     } else {
			     current[nextBranch] = { n };
			     }

			     }
			     
			     n.forEach(x => this.insert(x));
	
	}

	const bst = new BinarySearchTree([10, 7, 14, 5, 13]);
	[8, 18, 15, 6].forEach(x => bst.insert(x));

	const util = require('util');
	console.log(util.inspect(bst, false, null, true));