Eliminate any repeated elements in the array by utilizing TypeScript

Hey, I'm trying to figure out how to remove duplicate entries from an array where the UserId values are the same, and keep only one of each unique entry. Can anyone help me with this?

For example:

a=[
{userId:1,name:''},
{userId:2,name:''},
{userId:3,name:''},
{userId:1,name:''},
{userId:1,name:''}
]

Result should be:

a=[
{userId:1,name:''},
{userId:2,name:''},
{userId:3,name:''}
]

Answer №1

If you want to eliminate duplicates, you can achieve this by using the filter method in JavaScript:

    array.filter((item, index) => {
        const firstOccurrenceIndex = array.findIndex(innerItem => item.id === innerItem.id);
        return firstOccurrenceIndex === index;
    })

The findIndex function will always give you the index of the first element it encounters. This enables you to effectively remove duplicate entries from the array.

Answer №2

If you're looking to remove duplicates from an array, I suggest using the uniqBy function in lodash library. You can find more information about it here: https://lodash.com/docs/4.17.15#uniqBy

let uniqueArray = _.uniqBy(arrayToCheck, 'propertyName');

Answer №3

To optimize performance, consider using the following code snippet:

const uniqueKeys = new Set<number>()
const uniqueResults = []
for (const entry of array) {
    if (!uniqueKeys.has(entry.userId)) {
        uniqueKeys.add(entry.userId)
        uniqueResults.push(entry)
    }
}

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