Return Unique Values in Arrays

Question

As a result of below code, I am wanting to return only unique values. As an example, if there are three 'Company not found' items that will be returned in the array, I would like it to be written only once. Can anyone help?

function findInvalidCardCompanies(invalidCards) {
const invalidCompany=[];

for (let j=0; j<invalidCards.length; j++) {
let inv=invalidCards[j];
if(inv[1]===3) {invalidCompany.push('Amex')}
else if (inv[1]===4) {invalidCompany.push('Visa')}
else if (inv[1]===5) {invalidCompany.push ('Mastercard')}
else if (inv[1]===6) {invalidCompany.push('Discover')}
else {invalidCompany.push('Company not found')};
}
return invalidCompany;
};
console.log(findInvalidCardCompanies(findInvalidCards(batch)));

https://stackoverflow.com/questions/1960473/get-all-unique-values-in-a-javascript-array-remove-duplicates — WillD, Apr 19 '20 at 19:21
@WillD I saw it but couldn't figure out how to implement into my code above. — B_12, Apr 19 '20 at 19:24

Saadi · Accepted Answer · 2020-04-19T19:30:41.597

Use the javascript Set Object to remove the duplicate items. The Set object lets you store unique values of any type, whether primitive values or object references. More details here

 // Use to remove duplicate elements from the array 

const numbers = [2,3,4,4,2,3,3,4,4,5,5,6,6,7,5,32,3,4,5]

console.log([...new Set(numbers)]) 

// [2, 3, 4, 5, 6, 7, 32]

So your function will look something like this:

function findInvalidCardCompanies(invalidCards) {
const invalidCompany=[];

for (let j=0; j<invalidCards.length; j++) {
let inv=invalidCards[j];
if(inv[1]===3) {invalidCompany.push('Amex')}
else if (inv[1]===4) {invalidCompany.push('Visa')}
else if (inv[1]===5) {invalidCompany.push ('Mastercard')}
else if (inv[1]===6) {invalidCompany.push('Discover')}
else {invalidCompany.push('Company not found')};
}
return [...new Set(invalidCompany)];
};
console.log(findInvalidCardCompanies(findInvalidCards(batch)));

If I wanted to use if (invalidCompany.indexOf('Mastercard') === -1), what would be the best way to add it to code? Especially for the 'Company not found' part. — B_12, Apr 19 '20 at 19:46

score 0 · Answer 2 · answered Apr 19 '20 at 19:24

Use a Set. A value in the Set may only occur once; it is unique in the Set's collection.

You can add to a set with the add Function. If you add an already existing value, it will be ignored.

function findInvalidCardCompanies(invalidCards) {
const invalidCompany= new Set();

for (let j=0; j<invalidCards.length; j++) {
let inv=invalidCards[j];
if(inv[1]===3) {invalidCompany.add('Amex')}
else if (inv[1]===4) {invalidCompany.add('Visa')}
else if (inv[1]===5) {invalidCompany.add ('Mastercard')}
else if (inv[1]===6) {invalidCompany.add('Discover')}
else {invalidCompany.add('Company not found')};
}
return invalidCompany;
};
console.log(findInvalidCardCompanies(findInvalidCards(batch)));

Return Unique Values in Arrays

2 Answers2