javascript - Issues with a recursive function when trying to create a BST using Pseudoclassical Inheritance -

so i'm trying create binary search tree using pseudoclassical inheritance. accepts array, sorts it, uses middle value starting point, , inserts remaining values array bst. guess i'm trying best utilize functional programming (correct me if i'm wrong please) using reuseable methods , because bst insert method needs recursive.

i've pointed out code errors out. believe takes 3 initial value, believe 1 (the next value in array) gets inserted, believe number 2 error occurs when says "typeerror: this.left.insert not function". can point out i'm doing wrong? why won't insert method call this.left?

    var noduplicatesbst = function(array) {       var temparr = arguments[0].sort(function(a, b) {         return a-b;       });       var middle = math.floor(((temparr.length - 1) / 2));       var sliced = temparr.splice(middle, 1);        this.createbst(sliced[0]);        // insert rest of temparr bst       (var = 0; < temparr.length; i++) {         this.insert(temparr[i]);       }     };      noduplicatesbst.prototype.createbst = function(number) {       this.value = number;       this.left = null;       this.right = null;     };      noduplicatesbst.prototype.insert = function(number) {       if (number < this.value) {         if (this.left === null) {           this.left = new this.createbst(number);         } else { // ------------code below not work!, lined 77 probably. typeerror: this.left.insert not function----------------------           this.left.insert(number);         }       } else if (number > this.value) {         if (this.right === null) {           this.right = new this.createbst(number);         } else {           this.right.insert(number);         }       } else {         // nothing       }     };      var testbst = new noduplicatesbst([2,3,4,5,1]);      console.log("the testbst:", testbst); 

that's not written in functional way, take , try go thru tutorial learn more functional programming in js: http://reactivex.io/learnrx/

and original question why see "typeerror: this.left.insert not function". check comments in code:

var noduplicatesbst = function(arr) {    var middle, left = [], center, right = [];    if (!array.isarray(arr) || arr.length == 0) {      return this;    }    if (arr.length == 1) {      center = arr[0];    } else {      middle = math.floor((arr.length / 2));      center = arr[middle];      left = arr.slice(0, middle);      right = arr.slice(middle + 1, arr.length);      console.log('left:', left);      console.log('middle:', center);      console.log('right:', right);    }      this.createbst(center);      // insert left , right parts bst    if (left.length > 0) {      this.insert(left);    }    if (right.length > 0) {      this.insert(right);    }  };    noduplicatesbst.prototype.createbst = function(number) {    this.value = number;    this.left = null;    this.right = null;  };    noduplicatesbst.prototype.insert = function(arr) {    if (arr.length > 0) {      //array sorted , took middle element, can compare first element      if (arr[0] < this.value) {        /** here use createbst constructor, creates new element,        left , right values, break prototypal inheritance chain,        that's why don't have access insert function */        // this.left = new this.createbst(number);        // it's better pass part of array build tree further        this.left = new noduplicatesbst(arr);      } else {        this.right = new noduplicatesbst(arr); //the same above      }    }  };    var arr = [2, 3, 4, 5, 1];  var temparr = arr.reduce(function (noduplicatesarr, current) { //remove duplicates    if (noduplicatesarr.indexof(current) === -1) {      noduplicatesarr.push(current);    }      return noduplicatesarr;  }, []).sort(function(a, b) {    return - b;  });  var testbst = new noduplicatesbst(temparr);  console.log("the testbst:", testbst);

for prototypal chain inheritance check: https://developer.mozilla.org/en/docs/web/javascript/inheritance_and_the_prototype_chain

btw. changed code accept arrays instead of numbers, build bst