get only the unique value of an array

Question

I am new to javascript and I tried like using distinct but its not what im looking for

example array:

let arr = [ {key:\"1\",value:\"dog\"},
                 


        

Answer 1

You can use reduce and Map

let arr = [{key:"1",value:"dog"},{key:"1",value:"dog"},{key:"2",value:"cat"},{key:"3",value:"bird"},{key:"3",value:"bird"}]

let mapper = arr.reduce( (op,inp) => {
  let {key} = inp
  op.set(key, op.get(key) || {value: inp, count:0})
  op.get(key).count++
  return op
},new Map())


let final = [...mapper.values()].reduce((op,{value,count}) => {
   if(count === 1){
    op.push(value)
   }
   return op
},[])

console.log(final)