Simple TreeMap (no balancing)

simple_treemap.js

class TreeMap {

  constructor(){
    this.root = null
  }

  get(key){
    return this.doGet(key, this.root)
  }

  doGet(key, current){
    if(current == null){
      return null
    }
    if(current.key == key){
      return current.value
    }
    return this.doGet(key, current.key < key ? current.right : current.left)
  }

  set(key, value, current){
    if(this.root == null){
      this.root = {key, value}
    } else {
      this.doSet(key, value, this.root)
    }
  }

  doSet(key, value, current){
    if(current.key == key){
      current.value = value
    } else if(current.key < key){
      if(current.right == null){
        current.right = {key, value}
      } else {
        this.doSet(key, value, current.right)
      }
    } else {
      if(current.left == null){
        current.left = {key, value}
      } else {
        this.doSet(key, value, current.left)
      }
    }
  }

  list(){
    var result = []
    this.doList(result, this.root)
    return result
  }

  doList(result, current){
    if(current == null){
      return
    }
    this.doList(result, current.left)
    result.push({key: current.key, value: current.value})
    this.doList(result, current.right)
  }
}


var map = new TreeMap()

map.set(3, 'three')
map.set(7, 'seven')
map.set(1, 'one')
map.set(2, 'two')
map.set(0, 'zero')
map.set(10, 'ten')
map.set(9, 'nine')


console.log(map.list())
console.log(map.get(9))