001.js

/**
 001: Write a Solver class/object in Javascript that would accept an array in the form of:
 [3, “Plus”, 1], [6, “Times”, 2]... or an object with properties “operand1”, “operator” and “operand2”,
 the option that you prefer, and returns the result of the arithmetics.
 Note: element representing the operator is the name of a function or a reference to that function –
 implement them as well (Plus, Minus, Times and Divide).
 Note: in the future there may be a need to support another operations without changing the existing
 code or changing it as little as possible.
  */


var Solver = function (){

    var results = [];

    for(var i in arguments){
        results.push( SolveItem(arguments[i]) );
    }

    return results;
}

var SolveItem = function (operation) {
    var self = this,
    operand1 = parseInt(operation[0], 10),
    operator = operation[1],
    operand2 = parseInt(operation[2], 10);

    function Plus(a, b){
        return a + b;
    }

    function Minus(a, b){
        return a + b;
    }

    function Times(a, b){
        return a * b;
    }

    function Divide(a, b){
        return a / b;
    }

    switch (operator) {
        case 'Plus':
            total = Plus(operand1, operand2);
            break;
        case 'Minus':
            total = Minus(operand1, operand2);
            break;
        case 'Times':
            total = Times(operand1, operand2);
            break;
        case 'Divide':
            total = Divide(operand1, operand2);
            break;

        default:
            //It could have been an alert, an exception, but a console error will be visible during development
            console.error('"' + operator + '" is not within the valid operations for this function: ' + typeof self );
            break;
    }

    return total;
};

var total = Solver([2, "Plus", 1], [12, "Plus", 1]);

console.log(total);