Add Count method (#36)

.vscode/settings.json

@@ -0,0 +1,5 @@
+{
+    "eslint.enable": false,
+    "jshint.enable": false,
+    "tslint.enable": false
+}

index.d.ts

@@ -3,15 +3,16 @@ interface Array<T> {
   Aggregate<T>(accum: (memo: T, val: T) => T): T;
   All<T>(predicate: (X: T) => boolean): boolean;
   Concat<T>(list: Array<T>)  : Array<T>;
+  Count<number>(): number;
   ElementAt<T>(index: number): T;
   First<T>(): T;
   First<T>(predicate: (x: T) => boolean): T;
   Last<T>(): T;
   Prepend<T>(element: T): Array<T>;
   Reverse<T>(): Array<T>;
   Select<T, U>(xform: (x: T) => U): Array<U>;
+  Sum<number>(): number;
   TakeWhile<T>(predicate: (X: T) => boolean): Array<T>;
   Union<T>(adder: Array<T>): Array<T>;
   Where<T>(predicate: (X: T) => boolean): Array<T>;
-  Sum<number>(): number;
 }

index.js

@@ -1,33 +1,35 @@
 const Aggregate = require('./src/Aggregate');
 const All = require('./src/All');
 const Concat = require('./src/Concat');
+const Count = require('./src/Count');
 const ElementAt = require('./src/ElementAt');
 const First = require('./src/First');
 const Last = require('./src/Last');
 const Prepend = require('./src/Prepend');
 const Reverse = require('./src/Reverse');
 const Select = require('./src/Select');
+const Sum = require('./src/Sum');
 const TakeWhile = require('./src/TakeWhile');
 const ToDictionary = require('./src/ToDictionary');
 const Union = require('./src/Union');
 const Where = require('./src/Where');
-const Sum = require('./src/Sum');
 
 const bindAll = function() {
   Array.prototype.Aggregate = Aggregate;
   Array.prototype.All = All;
   Array.prototype.Concat = Concat;
+  Array.prototype.Count = Count;
   Array.prototype.ElementAt = ElementAt;
   Array.prototype.First = First;
   Array.prototype.Last = Last;
   Array.prototype.Prepend = Prepend;
   Array.prototype.Reverse = Reverse;
   Array.prototype.Select = Select;
+  Array.prototype.Sum = Sum;
   Array.prototype.TakeWhile = TakeWhile;
   Array.prototype.ToDictionary = ToDictionary;
   Array.prototype.Union = Union;
   Array.prototype.Where = Where;
-  Array.prototype.Sum = Sum;
 };
 
 module.exports = bindAll;

src/Count.js

@@ -0,0 +1,5 @@
+function Count() {
+    return this.length;
+}
+
+module.exports = Count;

test/Count.spec.js

@@ -0,0 +1,10 @@
+const expect = require('chai').expect;
+require('..')();
+
+describe('Array#prototype#Count', () => {
+    const input = [1, 2, 3];
+
+    it('should return correct length', () => {
+        expect(input.Count()).to.eql(input.length);
+    });
+});