Can you write a function that deeply flattens an array?

Question

Sigiloso · Accepted Answer

Depending on how the non-arrays must be handled, this function does the job if you can just return the argument when it's not an array:

function flatten(array) {
  if (!Array.isArray(array)) {
    return array;
  }
  
  return array.reduce((acc, cur) => {
    return acc.concat(flatten(cur));
  }, []);
}

Himanshu · Answer

function flatten (arr) {
    return arr.reduce(function (res, elem) {
        if (elem instanceof Array) {
            return res.concat(flatten(elem))
        } else {
            res.push(elem)
            return res;
        }
    }, [])
}

Sigiloso · Answer

let flat = (z = []) => {
            return !Array.isArray(z) ? 
                        [].concat(z) : 
                        (z.length > 0) ? flat(z.splice(0, 1)[0]).concat(flat(z)) : z
        }

Daniel · Answer

const flatten = (arr) =>  String(arr).split(',');

Handles deeply nested arrays, but will convert all values to string.

Meta

Pergunta de entrevista da empresa Meta

Respostas da entrevista

Empresas seguidas

Buscas de vagas