I am trying to flatten any length of a nested array into a single array. Why it's showing array rather than array value?
function flatten(arr) {
var res = [];
for (var i = 0; i < arr.length; i++) {
if (toString.call(arr[i]) === "[object Array]") {
res.push(flatten(arr[i]));
} else {
res.push(arr[i]);
}
}
return res;
}
console.log(flatten([1, 2, [3, [4, 5, [6]]], 7, 8]));
// [1, 2, Array(2), 7, 8]You are pushing to res the result of flatten, which is an array. Instead Array#concat the result of the inner flatten call to res, and assign the result to res.
Note: to identify an array, you can use Array#isArray.
function flatten(arr) {
var res = [];
for (var i = 0; i < arr.length; i++) {
if (Array.isArray(arr[i])) {
res = res.concat(flatten(arr[i]));
} else {
res.push(arr[i]);
}
}
return res;
}
console.log(flatten([1, 2, [3, [4, 5, [6]]], 7, 8])); // [1, 2, Array(2), 7, 8]You can use concat instead of push and reduce instead of for loop.
const flatten = data => data.reduce((r, e) => {
return r = r.concat(Array.isArray(e) ? flatten(e) : e), r
}, [])
console.log(flatten([1, 2, [3, [4, 5, [6]]], 7, 8]))You can use the flat() method on the array as follows.
function flatten(arr) {
return arr.flat(10) //the number in brackets are the depth level
}
console.log(flatten([1, 2, [3, [4, 5, [6]]], 7, 8]));