How solve .push is not a function in javascript

Question

const valid1 = [4, 5, 3, 9, 6, 7, 7, 9, 0, 8, 0, 1, 6, 8, 0, 8];

const validateCred = (arr) => {
    let newArr = []
    for (let i = 1; i < arr.length; i = i