hashtable.js

class HashTable {
  constructor( size ) {
    this.values = {};
    this.numberOfValues = 0;
    this.size = size;
  }
  add( key, value ) {
    let hash = this.calculateHash( key );
    if ( !this.values.hasOwnProperty( hash ) ) {
      this.values[ hash ] = {};
    }
    if ( !this.values[ hash ].hasOwnProperty( key ) ) {
      this.numberOfValues++;
    }
    this.values[ hash ][ key ] = value;
  }
  remove( key ) {
    let hash = this.calculateHash( key );
    if (
      this.values.hasOwnProperty( hash ) &&
      this.values[ hash ].hasOwnProperty( key )
    ) {
      delete this.values[ hash ][ key ];
      this.numberOfValues--;
    }
  }
  calculateHash( key ) {
    return key.toString().length % this.size;
  }
  search( key ) {
    let hash = this.calculateHash( key );
    if (
      this.values.hasOwnProperty( hash ) &&
      this.values[ hash ].hasOwnProperty( key )
    ) {
      return this.values[ hash ][ key ];
    } else {
      return null;
    }
  }
  length() {
    return this.numberOfValues;
  }
  print() {
    let string = '';
    for ( let value in this.values ) {
      for ( let key in this.values[ value ] ) {
        string += this.values[ value ][ key ] + ' ';
      }
    }
    console.log( string.trim() );
  }
}
let hashTable = new HashTable( 3 );
hashTable.add( 'first', 1 );
hashTable.add( 'second', 2 );
hashTable.add( 'third', 3 );
hashTable.add( 'fourth', 4 );
hashTable.add( 'fifth', 5 );
hashTable.print(); // => 2 4 1 3 5
console.log( 'length gives 5:', hashTable.length() ); // => 5
console.log( 'search second gives 2:', hashTable.search( 'second' ) ); // => 2
hashTable.remove( 'fourth' );
hashTable.remove( 'first' );
hashTable.print(); // => 2 3 5
console.log( 'length gives 3:', hashTable.length() ); // => 3
/*
       ~ js-files : (master) node hash.js
    2 4 1 3 5
    length gives 5: 5
    search second gives 2: 2
    2 3 5
    length gives 3: 3
    */