Javascript Data Structure Tutorial - Javascript HashTable

function HashTable() { /*from ww w  .j av a  2  s  .  c  om*/
    this.table = new Array(137); 
    this.simpleHash = simpleHash; 
    this.betterHash = betterHash; 
    this.showDistro = showDistro; 
    this.put = put; 
} 
function put(data) { 
    var pos = this.betterHash(data); 
    this.table[pos] = data; 
} 
function simpleHash(data) { 
    var total = 0; 
    for (var i = 0; i < data.length; ++i) { 
        total += data.charCodeAt(i); 
    } 
    console.log("Hash value: " + data + " -> " + total); 
    return total % this.table.length; 
} 
function showDistro() { 
    var n = 0; 
    for (var i = 0; i < this.table.length; ++i) { 
        if (this.table[i] != undefined){ 
            console.log(i + ": " + this.table[i]); 
        } 
    } 
} 

function betterHash(string) { 
    const H = 37; 
    var total = 0; 
    for (var i = 0; i < string.length; ++i) { 
        total += H * total + string.charCodeAt(i); 
    } 
    total = total % this.table.length; 
    if (total < 0) { 
        total += this.table.length-1; 
    } 
    return parseInt(total); 
} 

var someNames = ["D", "J", "A", "R", "C", "M", "B", "X", "J"]; 
var hTable = new HashTable(); 
for (var i = 0; i < someNames.length; ++i) { 
    hTable.put(someNames[i]); 
} 
hTable.showDistro();