idInvalidCardCompanies() function not working need help

https://www.codecademy.com/paths/full-stack-engineer-career-path/tracks/fscp-javascript-syntax-part-ii/modules/fecp-challenge-project-credit-card-checker/projects/credit-card-checker

i seem lost in this exercise but all I can come up Is with this for the credit card checker on step 4:
Here is my code: // All valid credit card numbers

const idInvalidCardCompanies = arr => {
let batch = ;
for(let i = 0; i < arr.length; i++)
var index = (arr[i][0]);
if(index === 4) {
batch.push(‘Visa’);
}

return batch;
}

I am getting an empty array returned

you are missing a set of { } that are needed for the for-loop.

Otherwise, you are checking if the index is 4 - outside the loop …
meaning its only doing the check using whatever index is after the loop runs.
(without the {}, only the first statement after the declaration of the loop is inside the loop.)

const idInvalidCardCompanies = arr => {
    let batch = ;
    for(let i = 0; i < arr.length; i++) // { needed here
      var index = (arr[i][0]);
      if(index === 4) {
        batch.push(‘Visa’);
      }
//  } needed here
    return batch;
}