Check if a value is an object in JavaScript

Question

How do you check if a value is an object in JavaScript?

Answer 1

OK, let's give you this concept first before answering your question, in JavaScript Functions are Object, also null, Object, Arrays and even Date, so as you see there is not a simple way like typeof obj === 'object', so everything mentioned above will return true, but there are ways to check it with writing a function or using JavaScript frameworks, OK:

Now, imagine you have this object that's a real object (not null or function or array):

var obj = {obj1: 'obj1', obj2: 'obj2'};

Pure JavaScript:

//that's how it gets checked in angular framework
function isObject(obj) {
  return obj !== null && typeof obj === 'object';
}

or

//make sure the second object is capitalised 
function isObject(obj) {
   return Object.prototype.toString.call(obj) === '[object Object]';
}

or

function isObject(obj) {
    return obj.constructor.toString().indexOf("Object") > -1;
}

or

function isObject(obj) {
    return obj instanceof Object;
}

You can simply use one of these functions as above in your code by calling them and it will return true if it's an object:

isObject(obj);

If you are using a JavaScript framework, they usually have prepared these kind of functions for you, these are few of them:

jQuery:

 //It returns 'object' if real Object;
 jQuery.type(obj);

Angular:

angular.isObject(obj);

Underscore and Lodash:

//(NOTE: in Underscore and Lodash, functions, arrays return true as well but not null)
_.isObject(obj);