Flatten a nested array

Flatten a nested array

const nestedArray = [1, [2, [3, [4, 5]], 6], 7, [8, 9]];
let result = [];

function flattenArray(arr) {
    arr.forEach(val => {
        if(Array.isArray(val)) {
            flattenArray(val);
        } else {
            result.push(val);
          }
    });
}

flattenArray(nestedArray);
console.log(result);