Persistence of a number

persistence.js

function digit_product(number) {
    let digit_product = 1;
    while (number) {
        digit_product *= number % 10;
        number = Math.floor(number / 10);
    }
    return digit_product;
}

function persistence(number) {
    if (number < 10) return 0;
    return persistence(digit_product(number)) + 1;
}

find = 1;
while (persistence(find) < 5) {
    find++;
}

console.log(find);

test_input_array = [10, 25, 39, 77];
test_input_array.map(number => console.log(number + " " + persistence(number)));

// console.log(persistence(999))
// console.log(find + " " + persistence(find));