It can be quite complicated to understand what needs to be done. There are always many ways to do something when coding but regardless of the algorithm used, we have to create a program that does the following:
It has to add two numbers passed as parameters and return the sum.
It has to check if any of the numbers are actual numbers, otherwise return undefined and stop the program right there.
It has to check if it has one or two arguments passed. More are ignored.
If it has only one argument then it has to return a function that uses that number and expects another one, to then add it.
Every time you deal with an argument, you have to check if it is defined and if it is a number.
Hint 2
When working on the case that it needs to return a function, using closure can help you write the new function in terms of addTogether().
Hint 3
The early return pattern can simplify your code.
Solutions
Solution 1 (Click to Show/Hide)
function addTogether() {
const [first, second] = arguments;
if (typeof (first) === "number") {
if (typeof (second) === "number") return first + second;
if (arguments.length === 1) return (second) => addTogether(first, second);
}
}
Solution 2 (Click to Show/Hide)
function addTogether() {
const [first, second] = arguments;
// First argument is not a number
if (typeof(first) !== "number") {
return undefined;
}
// First argument is a number
// and second argument is not defined
else if (arguments.length === 1) {
function addSecond(second) {
// New argument is not a number
if (typeof(second) !== "number") {
return undefined;
}
// New argument is a number
else {
return first + second;
}
}
// Note: returning a *function*
return addSecond;
}
// First argument is a number
// and second argument is not a number
else if (typeof(second) !== "number") {
return undefined;
}
// First argument is a number
// and second argument is a number
else {
return first + second;
}
}
Solution 3 (Click to Show/Hide)
function addTogether() {
const [first, second] = arguments;
function addSecond(second) {
if (typeof (second) === "number") return first + second;
}
if (typeof (first) === "number") {
if (arguments.length === 1) return addSecond;
if (arguments.length === 2) return addSecond(second);
}
}
This is my solution. It is shorter but not sure if it is as robust as the āofficialā solutions. (I donāt see the need to use the āargumentsā object.)
function addTogether(a, b) {
// only if valid number provided
if (Number.isFinite(a)) {
if (!b) {
return function(c) {
if (Number.isFinite(c)) {
return a + c;
}
};
}
else if (Number.isFinite(b)) {
return a + b;
}
}
// returns undefined by default
}
addTogether(2,3);
Cleanest āBasic Code Solutionā I came up with so far (using the arguments object):
function addTogether() {
//Variable and subroutine declaration (optional, but makes code cleaner)
var args = arguments;
var a = args[0];
var b = args[1];
function isNum(num) {
return Number.isInteger(num);
}
//Actual program: relies on implicit return of 'undefined'
//Note: while refactoring I remove curly braces if not required
if (isNum(a)) {
if (isNum(b))
return a + b;
else if (!b)
return function(b) {
if (isNum(b))
return a + b;
};
}
}
In all of the examples, if you test something where you have one argument that is not a number, such as addTogether("string")(3); it always results in TypeError: addTogether(...) is not a function.
Why is this happening? And is there a way to avoid it?
Looks like this has been covered already, no surprise there
function addTogether() {
var len = arguments.length;
var a = arguments[0];
var b = arguments[1];
var isNum = function(arg) { return Number.isFinite(arg); };
if (len === 1 && isNum(a)) {
return function(x) {
if (isNum(x)) {
return a + x;
}
};
}
else if (len === 2 && isNum(a) && isNum(b)) {
return a + b;
}
}
Can someone please explain this to me? I cannot wrap my head around how to access the second argument if there is only one passed to the function. For example, in the callback addTogether(2)(3) how would I access the (3)? Arguments[1] does not do it cause itās not a second argument. Any help would be appreciated.
@sh4hidkh4n I still donāt understand but thank you for trying to explain. I will continue to look trough different solutions to try to understand. Are the any resources that I could read to learn more about this particular concept?
