JS20 array flattening

JS20 Flattening arrays

Answer key ： Recursive array judgment

let newarr = []
const _flatten = arr => {
    
    //  The completion code 
    let i = 0;
    while(i < arr.length) {
    
        if (Array.isArray(arr[i])) {
    
            _flatten(arr[i])
        } else {
    
            newarr.push(arr[i])
        }
        i++
    }
    return newarr
}