Filter out duplicates from a JSON array - json

Question

Lets say I have a JSON file with an array in it like this:
[
{
"distinct_id": "abc",
"properties": {
"bookID": "123",
"userID": "abc",
}
},
{
"distinct_id": "abc",
"properties": {
"bookID": "123",
"userID": "abc",
}
},
{
"distinct_id": "ced",
"properties": {
"bookID": "123",
"userID": "ced",
}
},
{
"distinct_id": "abc",
"properties": {
"bookID": "456",
"userID": "ced",
}
}
]
I am trying to figure out how I would loop through this and return a new array just one instance of each distinct_id (basically removing duplicates) - think of it like a an array of unique users.
I am using TypeScript. I was trying to use Set but that wasn't working.

Answer 1

interface Item {
distinct_id: string;
properties: {
bookID: string;
userID: string;
};
}
const getDistinctIds = (data: Item[]) => data.map(item => item.distinct_id);
const getUniqueDistinctIds = (data: Item[]) => Array.from(new Set(getDistinctIds(data)));
const getItemByDistinctId = (data: Item[], distinct_id: string) => data.find(item => item.distinct_id === distinct_id);
const getUniqueItems = (data: Item[]) => getUniqueDistinctIds(data).map(distinct_id => getItemByDistinctId(data, distinct_id));
const data: Item[] = [
{
"distinct_id": "abc",
"properties": {
"bookID": "123",
"userID": "abc",
}
},
{
"distinct_id": "abc",
"properties": {
"bookID": "123",
"userID": "abc",
}
},
{
"distinct_id": "ced",
"properties": {
"bookID": "123",
"userID": "ced",
}
},
{
"distinct_id": "abc",
"properties": {
"bookID": "456",
"userID": "ced",
}
}
];
const uniqueItems = getUniqueItems(data);
console.log(uniqueItems);
Here is link to TS PLAYGROUND