How can I check if an object is an array?
The method given in the ECMAScript standard to find the class of Object is to use the toString
method from Object.prototype
.
if(Object.prototype.toString.call(someVar) === '[object Array]') { alert('Array!');}
Or you could use typeof
to test if it is a string:
if(typeof someVar === 'string') { someVar = [someVar];}
Or if you're not concerned about performance, you could just do a concat
to a new empty Array.
someVar = [].concat(someVar);
There's also the constructor which you can query directly:
if (somevar.constructor.name == "Array") { // do something}
Check out a thorough treatment from T.J. Crowder's blog, as posted in his comment below.
Check out this benchmark to get an idea which method performs better: http://jsben.ch/#/QgYAV
From @Bharath, convert a string to an array using ES6 for the question asked:
const convertStringToArray = (object) => { return (typeof object === 'string') ? Array(object) : object}
Suppose:
let m = 'bla'let n = ['bla','Meow']let y = convertStringToArray(m)let z = convertStringToArray(n)console.log('check y: '+JSON.stringify(y)) . // check y: ['bla']console.log('check y: '+JSON.stringify(z)) . // check y: ['bla','Meow']
In modern browsers you can do:
Array.isArray(obj)
(Supported by Chrome 5, Firefox 4.0, Internet Explorer 9, Opera 10.5 and Safari 5)
For backward compatibility you can add the following:
// Only implement if no native implementation is availableif (typeof Array.isArray === 'undefined') { Array.isArray = function(obj) { return Object.prototype.toString.call(obj) === '[object Array]'; }};
If you use jQuery you can use jQuery.isArray(obj)
or $.isArray(obj)
. If you use Underscore.js you can use _.isArray(obj)
.
If you don't need to detect arrays created in different frames you can also just use instanceof
:
obj instanceof Array
I would first check if your implementation supports isArray
:
if (Array.isArray) return Array.isArray(v);
You could also try using the instanceof
operator
v instanceof Array