I have an array of data which looks like this.
data = [
{ "name": "Apple", "type": "Fruit"},
{ "name": "Cabbage", "type": "Vegetable"} ,
{ "name": "Orange", "type": "Fruit"}
]
I want to filter out the element which its type already existed.
And I want to keep the first element.
E.g. keep Apple instead of Orange
data = [
{ "name": "Apple", "type": "Fruit"},
{ "name": "Cabbage", "type": "Vegetable"}
]
Using Array#filter, you can iterate over the array while updating a Set to keep track of types added:
const data = [ { "name": "Apple", "type": "Fruit"}, { "name": "Cabbage", "type": "Vegetable"}, { "name": "Orange", "type": "Fruit"} ];
const typeSet = new Set();
const res = data.filter(({ type }) => {
if(typeSet.has(type)) return false;
typeSet.add(type);
return true;
});
console.log(res);
1) You can filter the result if type already not present in dict using filter and Set as:
data.filter((o) => (dict.has(o.type) ? false : dict.add(o.type, true)))
const data = [
{ name: "Apple", type: "Fruit" },
{ name: "Cabbage", type: "Vegetable" },
{ name: "Orange", type: "Fruit" },
];
const dict = new Set();
const result = data.filter((o) => (dict.has(o.type) ? false : dict.add(o.type, true)));
console.log(result)2) You can also use for..of and Set as:
const data = [
{ name: "Apple", type: "Fruit" },
{ name: "Cabbage", type: "Vegetable" },
{ name: "Orange", type: "Fruit" },
];
const dict = new Set(), result = [];
for (let o of data) {
if (!dict.has(o.type)) {
result.push(o);
dict.add(o.type);
}
}
console.log(result);