Added Min (#61)

index.d.ts

@@ -24,6 +24,8 @@ interface Array<T> {
     equalityComparer: IEqualityComparer<T>
   );
   Last<T>(): T;
+  Min<number>(): number;
+  Min<T>(xform: (x: T) => number): T;
   Max<number>(): number;
   Max<T>(xform: (x: T) => number): T;
   Prepend<T>(element: T): Array<T>;

index.js

@@ -7,6 +7,7 @@ const Empty = require('./src/Empty')
 const First = require('./src/First');
 const GroupJoin = require('./src/GroupJoin');
 const Last = require('./src/Last');
+const Min = require('./src/Min');
 const Max = require('./src/Max');
 const Prepend = require('./src/Prepend');
 const Reverse = require('./src/Reverse');
@@ -28,6 +29,7 @@ const bindAll = function() {
   Array.prototype.First = First;
   Array.prototype.GroupJoin = GroupJoin;
   Array.prototype.Last = Last;
+  Array.prototype.Min = Min;
   Array.prototype.Max = Max;
   Array.prototype.Prepend = Prepend;
   Array.prototype.Reverse = Reverse;

src/Min.js

@@ -0,0 +1,9 @@
+/**
+ * @template T
+ * @param {((x: T) => number)} xform
+ * @returns {T}
+ */
+function Min(xform = x => x) {
+  return this.reduce((a, b) => (xform(a) < xform(b) ? a : b));
+}
+module.exports = Min;

test/Min.spec.js

@@ -0,0 +1,20 @@
+const expect = require('chai').expect;
+require('..')();
+describe('Array#prototype#Min', function() {
+  const numInput = [1, 2, 3, 4, 5, 6];
+  it('Should return the min value in number array', function() {
+    const expected = 1;
+    const actual = numInput.Min();
+    expect(actual).to.eql(expected);
+  });
+  const objInput = [
+    { name: 'Bill', age: 32 },
+    { name: 'Jim', age: 13 },
+    { name: 'Bart', age: 25 }
+  ];
+  it('Should return the object with the min property value in object array', function() {
+    const expected = { name: 'Jim', age: 13 };
+    const actual = objInput.Min(x => x.age);
+    expect(actual).to.eql(expected);
+  });
+});