How to concat all this array into a single array:
[Array(10), Array(10), Array(10), Array(10), Array(10), Array(10), Array(10), Array(2)]
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Possible duplicate of Merge/flatten an array of arrays in JavaScript?Mohammad Usman– Mohammad Usman2018-03-02 10:02:50 +00:00Commented Mar 2, 2018 at 10:02
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3 Answers
You can use ES6's spread:
var arrays = [[1, 2], [3, 4], [5, 6]];
var res = [].concat(...arrays);
console.log(res);
2 Comments
T.J. Crowder
Good thought making use of
concat's handling of multiple arguments.T.J. Crowder
@Bikshu s (and lurkers): If you can't use spread, the above is effectively:
var res = Array.prototype.concat.apply([], arrays);Use reduce and concat
var output = arr.reduce( (a, c) => a.concat(c), []); //assuming arr is the input array
Edit
As @TJ mentioned in his comment, that above solution will create some intermediate arrays along the way, you can try (concat without spread)
var output = [].concat.apply([], arr);
or
var output = Array.prototype.concat.apply([], arr); //avoiding usage of another unnecessary array `[]`
3 Comments
T.J. Crowder
Producing unnecessary intermediate arrays along the way... :-)
gurvinder372
@T.J.Crowder unnecessary intermediate arrays True, Or
[].concat.apply([], arr) would sufficeT.J. Crowder
Or you could avoid that last unnecessary array like this.
var array1 = ['a', 'b', 'c'];
var array2 = ['d', 'e', 'f'];
console.log(array1.concat(array2));
// expected output: Array ["a", "b", "c", "d", "e", "f"]
If you have an array of array you can do like so :
let bigArray = new Array();
arrayOfArray.forEach((arr) => {
bigArray.concat(arr);
});
