usage_of_reduce_in_javascript.js

/**
 * @author Sri Teja <[email protected]>
 * @link sri-teja.github.io
 */

// Syntax: 
//        <array>.reduce(<function>, start_value);

// The reduce () method reduces the array to a single value. 
// The reduce() method executes a provided function for each value 
// of the array (from left-to-right). 
// The return value of the function is stored in an accumulator (result/total).

// Example1:
function multiply(a,b){ return a*b; }

result = [2,3,4].reduce(multiply, 1); //result gives 24 = 2*3*4.

// Let's see how this works in detail
// step1: a=1 and b=2; return value from multiply() is 1*2 = 2;
// step2: a=2(the previous return value from the multiply()) and b=3;
//        return value from mutiply() is 2*3 = 6;
// step3: a=6 and b=4; return value from multiply() is 6*4 = 24;

// Another Example given below

// Example2:
function sum(a,b){ return a+b; }

result = [1,2,3].reduce(sum, 0); //result gives 6 = 1+2+3.