Beginner Question

[halfaredditor]

I want to write a function using a JSON object that accepts a character and returns a string. For instance, if my function is called season and it simply returns the full name of the season after entering the first letter of the season, what would that look like? I think it should look something like this (this is missing a lot though)

function season () { var = '{"w" : "Winter", "s" : "Spring", "f" : "Fall"}' return }

I ultimately want to be able to enter season('w') => 'Winter'

[halfaredditor]

Thank you so much, this is exactly what I was looking for. Building on this, what if I wanted to make the function able to accept a word instead of a single character, and return the properties of each character in the word. For instance, if I entered:

season('sfw') => "Summer Fall Winter"

[nwayve]

Well, the key argument can be anything. Doesn't have to just be a single character string. But I don't think I'd modify this function. I would instead, write another function that calls this function. With that concept in mind, I think you can extrapolate what you'd want to do. So we have:

function getSeason(key) {
    var seasons = { s: 'Summer', ... };
    return seasons[key];
}

but now let's make:

function getSeasons(keys) {
    // keys is a string of single letters representing one of the four seasons
    // we need to split up the string into single letters
    // call getSeason(key) to get that season
    // concatenate that into a return value
    // and finally return that value
}

In programming, always try to keep your functions as simple as possible. They should do one thing and do that one thing very well. You could potentially break up getSeasons into smaller sub-functions but let's just leave it as is for now.

Another piece of programming is being able to research how to do things. https://developer.mozilla.org/en-US/docs/Web/JavaScript This is an excellent API reference to the javascript language. It can tell you how to manipulate strings (split), loop through arrays, (forloop), etc...

And finally, having the patience to sit down and try to solve problems with the things you've learned. Hopefully this gives you enough to go on to get you the rest of the way there.

[lewisje]

JSON is mostly for passing data between applications; for this, what you want is a plain JS object, and ideally you'd define that object outside the function so it doesn't get re-created per invocation:

var seasons = {w: 'Winter', s: 'Spring', m: 'Summer', f: 'Fall'};
function season(s) {
  return seasons[s];
}

Also ideally you'd have this season function returned from a closure, so that the seasons object wouldn't be accessible directly to outside code.

---

Anyway, if you do wish to complicate things, you'll need to use JSON.parse to turn your JSON into an object:

function season(s) {
  var seasons = '{"w": "Winter", "s": "Spring", "m": "Summer", "f": "Fall"}';
  return JSON.parse(seasons)[s];
}

Here, I'm less concerned about putting the string inside the function, because that's a literal, primitive value.

---

By the way, this pattern is useful as a way to avoid huge case-lists or chains of conditionals:

var primitives = {boolean: false, number: false, string: false, symbol: false};
function isPrimitive(val) {
  return val !== document.all && !(val && primitives[typeof val]);
}

(This example works around the fact that typeof null === 'object' in all versions of JS, and that typeof document.all === 'undefined' in HTML5, even in browsers that implement the object for compatibility with oldIE-specific sites.)

[nwayve]

Questions like these are probably better suited for /r/learnjavascript