JAVASCRIPT

how to find duplicate item in array of object in javascript

const values = [
  { name: 'someName1' },
  { name: 'someName2' },
  { name: 'someName3' },
  { name: 'someName1' }
]

const uniqueValues = new Set(values.map(v => v.name));

if (uniqueValues.size < values.length) {
  console.log('uniqueValues')
}

find only duplicate data javascript object

const data = [{id: 1, order_id: 1}, {id: 2, order_id: 1}, {id: 3, order_id: 2}]
const duplicates = data.filter((item, index) => 
index !== data.findIndex((v) => v.order_id === item.order_id));

console.log(duplicates)

find duplicate values in array object javascript

const values = [{id: 10, name: 'someName1'}, {id: 10, name: 'someName2'}, {id: 11, name:'someName3'}, {id: 12, name: 'someName4'}];

const lookup = values.reduce((a, e) => {
  a[e.id] = ++a[e.id] || 0;
  return a;
}, {});

console.log(values.filter(e => lookup[e.id]));
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find only duplicate data javascript object

export const findDuplicate = (data: Record<string, any>[]): number[] => {
	const duplicates: number[] = data
		.filter((item: Record<string, any>, index: number) => index !== data.findIndex((v: Record<string, any>) => v.order_id === item.order_id))
		.map((val: Record<string, any>) => val.id)

	return duplicates
}

find duplicate values in array object javascript

duplicateIds = arr
     .map(e => e['id'])
     .map((e, i, final) => final.indexOf(e) !== i && i)
     .filter(obj=> arr[obj])
     .map(e => arr[e]["id"])