JavaScript map a JSON response into a new Array

Question

I have a script that pulls responseText from a website and parses it into JSON. An example of the output looks like this:

ctiResponse = [
    "Category / Type1 / Item1",
    "Category / Type1 / Item2",
    "Category / Type1 / Item2",
    "Category / Type1 / Item3",
    "Category / Type2 / Item1",
    "Category / Type2 / Item2",
    "Category / Type2 / Item2",
    "Category / Type2 / Item3",
    "Category / Type3 / Item1",
    "Category / Type3 / Item2",
    "Category / Type3 / Item2",
    "Category / Type3 / Item3",
];

I think the .map() function is what I need to use to accomplish my end result, but I'm not sure how to go about it. I'd like to create another array from the parsed JSON response that would end up like the following. Note that the parsed JSON response has repeated Items, and I only need those once in the second array.

let ctis = [
    {
        "Category": [
            "Type1": {"Item1", "Item2", "Item3"},
            "Type2": {"Item1", "Item2", "Item3"},
            "Type3": {"Item1", "Item2", "Item3"},
            ],
    }
]

"parses it into JSON" You deserialise/parse JSON in to a JavaScript object and serialise/stringify an object to JSON. It looks like you have a JavaScript array and therefore the question doesn't appear to be JSON related. — phuzi
– phuzi, Commented Aug 5, 2022 at 12:44
You desired result, does the list of items has to be an object or can it be an array? — Wimanicesir
– Wimanicesir, Commented Aug 5, 2022 at 12:45
Your desired result is not valid - array items do not have property names ("Type1", "Type2" etc.) — phuzi
– phuzi, Commented Aug 5, 2022 at 12:47

Mateusz Rorat · Accepted Answer · 2022-08-05 13:14:20Z

1

const ctiResponse = [
    "Category / Type1 / Item1",
    "Category / Type1 / Item2",
    "Category / Type1 / Item2",
    "Category / Type1 / Item3",
    "Category / Type2 / Item1",
    "Category / Type2 / Item2",
    "Category / Type2 / Item2",
    "Category / Type2 / Item3",
    "Category / Type3 / Item1",
    "Category / Type3 / Item2",
    "Category / Type3 / Item2",
    "Category / Type3 / Item3",
];

console.log(
  ctiResponse.reduce(
    (obj, line) => {
      const [category, type, item] = line.split(' / ');
      obj[category] = {...obj[category]}
      obj[category][type] = [...new Set([...obj[category][type] || [], item])];
        return obj;
    }
  , {}) 
)

edited Aug 5, 2022 at 13:14

answered Aug 5, 2022 at 12:53

Mateusz Rorat

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3 Comments

Ryan Bell Over a year ago

This gets me where I want to go, however, I don't want duplicate Items in the Type arrays.

Mateusz Rorat Over a year ago

obj[category][type] = [...new Set([...obj[category][type], item])]; add some thing like this. Set will remove duplicates

Ryan Bell Over a year ago

obj[category][type] = [...new Set([...obj[category][type] || [], item])]; works. Thank you @mateusz-rorat

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