Javascript Hash Table

better-hash-function.js

function hash(string) {
  let index = 0;
  for(let i = 0; i < string.length; i++) {
    index += string.charCodeAt(i) * i;
  }

  return index % _size;
}

collision-detection.js

function HashTable(size) {
  const _size = size;
  const _store = [];

  function hash(string) {
    let index = 0;
    for(let i = 1; i <= string.length; i++) {
      index += string.charCodeAt(i) * i;
    }

    return index % _size;
  }

  return {
    setElement(key, element){
      if(!_store[hash(key)] || _store[hash(key)] && _store[hash(key)][0] === key) {
        _store[hash(key)] = [key, element];
      }
      else {
        throw new Error("Collision!");
      }
    },
    getElement(key){
      if(_store[hash(key)]) {
        return _store[hash(key)][1];
      }

      return;
    }
  };
}

collision-resolution.js

function HashTable(size) {
  const _store = [];
  const _size = size;

  function hash(string) {
	  let index = 0;
	  for(let i = 0; i < string.length; i++) {
	    index += string.charCodeAt(i) * i + 1;
	  }
	
	  return index % _size;
	}

	function findMatchIndex(list, key) {
    for(let i = 0; i < list.length; i++) {
      if(list[i][0] === key) return i;
    }
  }

  return {
    dump() {
      console.dir(_store);
    },
	  setElement(key, element){
			if(!_store[hash(key)]) {
				_store[hash(key)] = [
					[key, element]
				];
			} 
			else {
			  const list = _store[hash(key)];
        const index = findMatchIndex(list, key);
        
				if(index) {
					return list[index] = [key, element];
				}

        list.push([key, element]);
			}
    },
	  getElement(key){
		  if(_store[hash(key)]) {
        const list = _store[hash(key)];
        const index = findMatchIndex(list, key);
        if(index) return list[index][1]
			}

			return;
	  }
  };
}

step-1.js

function HashTable(size = 10) {
    const _size = size;
    const _store = [];

    function hash(string) {
        return string.length % _size;
    }

    return {
        setElement(key, element) {
            _store[hash(key)] = element;
        },
        getElement(key){
            return _store[hash(key)];
        }
    };
}