JavaScript Hashtable Implementation

hashTable.js

function hashStringToInt(s, tableSize) {
  let hash = 17

  for (let i = 0; i < s.length; i++) {
    hash = (13 * hash * s.charCodeAt(i)) % tableSize
  }

  return hash
}

class HashTable {
  table = new Array(3)
  numItems = 0

  resize = () => {
    //create new arr double the size with newTable.length
    const newTable = new Array(this.table.length * 2)
    this.table.forEach(item => {
      if (item) {
        item.forEach(([key, value]) => {
          const idx = hashStringToInt(key, newTable.length)
          if (newTable[idx]) {
            newTable[idx].push([key, value])
          } else {
            newTable[idx] = [[key, value]]
          }
        })
      }
    })
    this.table = newTable
  }

  setItem = (key, value) => {
    //keep track of table leagth
    this.numItems++

    //monitor loadfactor and rezize table if over 80%  
    const loadFactor = this.numItems / this.table.length
    if (loadFactor > 0.8) {
      this.resize()
    }

    //if index exists push in to combined array
    const idx = hashStringToInt(key, this.table.length)
    if (this.table[idx]) {
      this.table[idx].push([key, value])
    } else {
      this.table[idx] = [[key, value]]
    }
  }

  getItem = key => {
    const idx = hashStringToInt(key, this.table.length)

    if (!this.table[idx]) {
      return null
    }

    // O(n)
    return this.table[idx].find(x => x[0] === key)[1]
  }
}

const myTable = new HashTable()
myTable.setItem("firstName", "bob")
myTable.setItem("lastName", "tim")
console.log(myTable.table.length) //3
myTable.setItem("age", 5)
myTable.setItem("dob", "1/2/3")
console.log(myTable.table.length) //6

console.log(myTable.getItem("firstName")) //bob
console.log(myTable.getItem("lastName"))  //tim
console.log(myTable.getItem("age")) //5
console.log(myTable.getItem("dob")) //1/2/3