hashTable.js

'use strict';

var hashSize = 3; // small so we get collisions
var hashArray = new Array(hashSize);
var bigPrime = 1223;

function calculateHash(key) {
	var hash = 0;
	if(key.length > 0){
		for (var i = 0; i < key.length; i++) {
			hash += key.charCodeAt(i);
		}
	}
	return (hash * bigPrime) % hashSize;
}

function set(key) {
	var existingObj = exists(key);
	
	if( existingObj ){
		hashArray[calculateHash(key)] = {
			data: key,
			next: existingObj
		};			
	} 
	else {
		hashArray[calculateHash(key)] = {
			data: key,
			next: null
		};	
	}
}

function exists(key) {
	if( hashArray[calculateHash(key)] ){
		return hashArray[calculateHash(key)];
	}
	return false;
}

function get(key) {
	var existingObj = exists(key);
	if(existingObj) {
		return equals(key, existingObj);
	}
	return null;
}

function equals(key, obj) {
	if(key == obj.data) {
		return obj;
	}
	else if(obj.next) {
		return equals(key, obj.next);
	}
	else {
		return null;
	}
}

// test collisions
set("chris");
set("andy");
set("william");
set("hart");
set("dubbs");
console.log(hashArray);
console.log(get("andy"));
console.log(get("dubbs"));