Advanced_functions-with_tests

TASK № 1

Write a function called "cache". It will be a function wrapper, which takes a function and caches its results depending on the arguments that were applied to the function.

let complexFunction = function(arg1, arg2) {
	return arg1 + arg2;  // just for example (any logic can be here)
 };

let cachedFunction = cache(complexFunction);

Example:

cachedFunction('foo', 'bar'); // complex function should be executed
cachedFunction('foo', 'bar'); // complex function should not be invoked again,
                      // instead the cached result should be returned
cachedFunction('foo', 'baz'); // should be executed,
            // because the method wasn't invoked before with these arguments

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TASK № 2

Create an object called "forwardBackwardSteps”. It should include 3 methods: “forward", “backward", “revealStep” and one property: “step”. Initial value of “step” is equal to 0. The object should support chaining calls on its methods. "forward" – increasing "step", "backward" – decreasing “step”, "revealStep" – console.log current value of "step".

Example:

forwardBackwardSteps.forward().forward().backward().forward().revealStep(); // 1+1-1+1 = 2

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TASK № 3

Write a function called “applyAll”. It takes a function (sum or mul) and an arbitrary number of arguments. It should call a received function ( output the “sum” and “mul” functions) with all arguments and return result. Using of call method is mandatory.

Example:

applyAll(sum, 1, 2, 3); // -> sum(1, 2, 3) = 6
applyAll(mul, 2, 3, 4); // -> mul(2, 3, 4) = 24

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* Don`t change the given functions naming and don't delete this part of code:

module.exports = { cache, ladder, applyAll, sum, mul }