Data structures and algorithms using javascript. Computer science FTW.

snippets.js

var array = [0, 1, 2];
var weekDays = ['sun','mon','tues','wed','thurs','fri','sat'];

var str = "test";
var obj = {};

for (var i = 0; i < array.length; i++) {
  var test = array[i];
}

//class
function MyFunc() {
  return true;
}

MyFunc.prototype.isEnabled = true;

// string reverse
MyFunc.prototype.reverse = function(str) {
    var arr = [];
    var len = str.length; 

    for (var i = 0; i <= len; i++) {
        arr.push(str.charAt(len - i))
    }

    return arr.join('');
}

MyFunc.prototype.reverse2 = function function(s){
    return s.split('').reverse().join('');
}

// for...in
for (var variable in obj) {
  if (obj.hasOwnProperty(variable)) {
  }
}

// switch
switch (str) {
  case 'test':

    break;
  default:

}

// sorting - based on quicksort http://en.cppreference.com/w/cpp/algorithm/qsort
// http://www.nczonline.net/blog/2012/11/27/computer-science-in-javascript-quicksort/
var arr =["qwe","qwerty"]
arr.sort(function(a, b){
  return b.length - a.length; // ASC -> a - b; DESC -> b - a
});

// array rotate
function rotate(arr, n) { 
  return arr.slice(n, arr.length).concat(arr.slice(0, n));
}

// stack LIFO (last in, first out)
var stack = [];
stack.push(2);       // stack is now [2]
stack.push(5);       // stack is now [2, 5]
var i = stack.pop(); // stack is now [2]
alert(i);            // displays 5

// queue FIFO (first in, first out)
var queue = [];
queue.push(2);         // queue is now [2]
queue.push(5);         // queue is now [2, 5]
var i = queue.shift(); // queue is now [5] since shift removes from 'front' of array
alert(i);              // displays 2

// Hashtables are js objects, silly
// constructing hashtable class
function HashTable(obj)
{
    this.length = 0;
    this.items = {};
    for (var p in obj) {
        if (obj.hasOwnProperty(p)) {
            this.items[p] = obj[p];
            this.length++;
        }
    }
}
// usage: 
var h = new HashTable({one: 1, two: 2, three: 3, "i'm no 4": 4});

// Map - returns a collection of headlines
var headlines = Array.prototype.slice.call(document.getElementsByTagName('h3'))
  .map(function(node) {
    return node.innerText;
});

Data structures

https://github.com/chenglou/data-structures

Stack & Queue
Hash table
read: http://www.mojavelinux.com/articles/javascript_hashes.html

Graphs
read: http://montague.io/2014/02/05/using-javascript-to-build-an-undirected-graph/ (undirected graph)

Binary Search Tree (BST)
read: http://www.nczonline.net/blog/2009/06/09/computer-science-in-javascript-binary-search-tree-part-1/

Linked Lists
read: http://www.nczonline.net/blog/2009/04/13/computer-science-in-javascript-linked-list/

Algorithms

Binary search
read: http://www.nczonline.net/blog/2009/09/01/computer-science-in-javascript-binary-search/
Gist: https://gist.github.com/bradoyler/d6db8c4223c9d855e324

Quick sort
read: http://www.nczonline.net/blog/2012/11/27/computer-science-in-javascript-quicksort/
C++ quicksort http://en.cppreference.com/w/cpp/algorithm/qsort (used in Chrome, IE)

Merge sort
http://www.nczonline.net/blog/2012/10/02/computer-science-and-javascript-merge-sort/
(used in Firefox, Safari)

Bubble sort (for kicks)
read: http://www.nczonline.net/blog/2009/05/26/computer-science-in-javascript-bubble-sort/

Breadth-first search - BFS (tree or graph traversal)
example: https://gist.github.com/kevinfjbecker/1524215

Depth-first search - DFS (tree or graph traversal)
example of many Graph algorithms: https://github.com/devenbhooshan/graph.js

Asymptotic notation
Big O