hash-table.js

class HashTable {
  constructor(size) {
    this.keyMap = new Array(size);
  }

  _hash(key) {
    let total = 0;

    const WEIRD_PRIME = 31;

    for (let i = 0; i < Math.min(key.length, 100); i++) {
      const char = key[i];
      const charCode = char.charCodeAt(0) - 96;

      total = (total * WEIRD_PRIME + charCode) % this.keyMap.length;
    }
    return total;
  }

  set(key, value) {
    const index = this._hash(key);
    if (!this.keyMap[index]) {
      this.keyMap[index] = [];
    }
    this.keyMap[index].push([key, value]);

    return this;
  }

  get(key) {
    const index = this._hash(key);
    if (this.keyMap[index]) {
      for (let i = 0; i < this.keyMap[index].length; i++) {
        if (this.keyMap[index][i][0] === key) {
          return this.keyMap[index][i][1];
        }
      }
    }
  }
}

const ht = new HashTable(20);