Cast string as array

Question

How, in Javascript, can I cast a string as an array in the same way that PHP (array) does.

//PHP
$array = (array)"string"

Basically I have a variable that can be an array or a string and, if a string, I want to make it an array using an inline command.

There is casting in JS but it is seldom used (just like in PHP). A common use is to treat a number as a string or a string as a number. "1" + "1" = "11" if you are not careful. — Levi Botelho, Oct 27 '12 at 18:29
You want to make it an Array of what? Should it be an Array of individual characters in the string? Or an Array that has the entire string at its first index? — I Hate Lazy, Oct 27 '12 at 18:34

score 41 · Answer 1 · answered Sep 27 '13 at 19:36

41

Hacky, but works:

[].concat(arrayOrString);

//Usage:
[].concat("a");
//["a"]
[].concat(["a"]);
//["a"]

answered Sep 27 '13 at 19:36

Pedro Nascimento

13,136
4
36
64

3

[Note] This is rather slow compared to the alternative: http://jsperf.com/array-coerce – Metalstorm Jan 23 '14 at 13:39
@Metalstorm Was it used in the same way? jsperf is currently down and I cannot check. – jeromej Jul 01 '15 at 03:17
@JeromeJ yes, it compares `concat` with `Array.isArray()`. The difference is noticeable. – Enrico Sep 14 '15 at 15:26
1

@Zim Ah thanks! Way faster indeed but sadly less beautiful: `Array.isArray(obj) ? obj:[obj]` – jeromej Sep 14 '15 at 18:00
This was the only solution I could find that would allow me to transform a string property to array inside a foreach statement. `([].concat(foo.bar.stringOrArray)).forEach((item) => {...})` – Kerry Johnson Jun 18 '22 at 18:25

Yanick Rochon · Accepted Answer · 2022-04-28T14:17:51.013

JavaScript is a prototyping language and does not have a type casting system.

One solution would be to check if your variable is a string and convert it into an array. For example :

if (typeof someVariable === 'string') someVariable = [someVariable];

In PHP, if you do a check on a string, like (ex: $array = 'string';) :

$array = (array) $array;  // ex: "string" becomes array("string")

The JavaScript equivalent will be

arr = typeof arr === 'string' ? [arr] : arr;

If your variable arr is not necessarily a string, you may use instanceof (edit: or Array.isArray) :

arr = arr instanceof Array ? arr : [arr];
arr = Array.isArray(arr) ? arr : [arr];

score 7 · Answer 3 · answered Oct 27 '12 at 18:27

7

var str    = "string";
var array  = str.split('');

console.log(array); // ['s', 't', 'r', 'i','n','g']

answered Oct 27 '12 at 18:27

Andre Meinhold

5,087
3
21
29

3

in PHP doing `str = (array)"string"` results in `array("string")` not `array('s','t','r','i','n','g')`. – Yanick Rochon Oct 27 '12 at 18:31
Any way I was looking for ['s', 't', 'r', 'i','n','g'] from "string". THX – MrHIDEn Apr 24 '14 at 13:03
`str_split($my_string)` in PHP btw. – jeromej Sep 14 '15 at 18:03
If that's what you want (and not what the OP was asking for), then just use `Array.from()` see MDN notes [https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/from] – Tom Auger Dec 13 '18 at 22:49

score 4 · Answer 4 · answered Aug 08 '13 at 09:03

4

You can in jQuery...

var arr = "[1,2,3,4,5]"; 
window.x = $.parseJSON(arr);
console.log(x);//cast as an array...

it works even if you have something like

[{"key":"value"}]

However this may NOT work if you have something like this...

[{key:"value"}] // different is the " (double quotes) on key

answered Aug 08 '13 at 09:03

Val

17,336
23
95
144

1

You don't need jQuery for that (Any more) , JSON.parse(arr); works the same. – t.mikael.d Jun 19 '17 at 13:01

score 3 · Answer 5 · answered Mar 18 '15 at 22:36

3

Turn a string into an array:

var myString = "['boop','top','foo']";
var myArray = JSON.parse(myString)

answered Mar 18 '15 at 22:36

Don P

60,113
114
300
432

score 1 · Answer 6 · answered Oct 27 '12 at 18:32

1

Just do like this

"sample".split("");

and you'll get

["s", "a", "m", ...]

answered Oct 27 '12 at 18:32

vyakhir

1,714
2
17
21

If you have something like: "[10,20,34,0]" and you want it to be: [10,20,34,0], your solution won't work. – jartaud May 03 '18 at 19:53

score 0 · Answer 7 · answered Oct 27 '12 at 18:29

0

You cannot cast to Array in JS but a simple ternary operation can do what you want.

var str = 'string';
var arr = (str instanceof Array) ? str : [ str ];

This works for any non-Array object or any primitive value. If you're sure that only actual Array objects and string primitives can be encountered here, the following is a bit faster:

var arr = (typeof str === 'string') ? [ str ] : str;

answered Oct 27 '12 at 18:29

J. K.

8,268
1
36
35

How does it compare with `Array.isArray(str) ? str:[str]`? – jeromej Sep 14 '15 at 18:08
1

**Update:** http://stackoverflow.com/questions/22289727/difference-between-using-array-isarray-and-instanceof-array > `Array.isArray` is a bit better. – jeromej Sep 14 '15 at 18:14

score 0 · Answer 8 · answered Oct 27 '12 at 18:29

0

"1,2,3".split(",") 
=> ["1", "2", "3"]

use split()

answered Oct 27 '12 at 18:29

AnandVeeramani

1,526
9
15

1

this is not the PHP equivalent asked in the question – Yanick Rochon Oct 27 '12 at 18:33

score 0 · Answer 9 · answered Sep 25 '13 at 18:48

0

Val's suggestion also works for strings which have array of arrays

var str = "[[1121,1],[1122,2],[1123,3]]";
var arr = $.parseJSON(str);
console.log(arr); //returns array of arrays

answered Sep 25 '13 at 18:48

Rahul

1
1

score 0 · Answer 10 · answered Nov 28 '17 at 10:14

0

You can also use the following if statement:

if(array instanceof Array != true) {array = [array];}

answered Nov 28 '17 at 10:14

jcwhall

63
4

grantwparks · Answer 11 · 2021-12-26T01:51:33.363

0

Array.isArray(foo) || (foo = [foo]);

or if that's not comfortable

foo = Array.isArray(foo) ? foo : [foo];

edited Dec 26 '21 at 01:51

answered Dec 11 '21 at 17:20

grantwparks

1,124
9
13

score -2 · Answer 12 · answered Mar 25 '18 at 21:24

-2

There is already a proposal for Array.flatten() and usable with babel-preset-stage-2.

const array = ['foo'].flatten()
console.log(array) // ['foo']

const array = [['foo', 'bar']].flatten()
console.log(array) // ['foo', 'bar']

answered Mar 25 '18 at 21:24

Philipp Kühn

1,579
2
16
25

Cast string as array

12 Answers12