How does instanceof work in javascript

It returns a boolean value if true then it indicates that the object is an instance of a particular class and if false then it is not. Skip to content. Change Language. Related Articles. JS Basics. JS Operators. JS Loops. JS Debugging. JS Methods. JS Math Object. It doesn't use constructor at all. Any and all of them will cause obj instanceof constructor to be true. In your examples, both obj2 and obj3 have Obj1 in their prototype chain. The instanceof operator,The instanceof operator allows to check whether an object belongs to a certain class.

It also takes inheritance into account. The instanceof operator tests whether a given object is an instance of a given JavaScript class. That works for most cases, but there are several cases where an object is not instanceof Object. The instanceof operator in JavaScript is used to check the type of an object at run time.

Ask Question. Asked 7 years, 4 months ago. Active 1 year, 4 months ago. Viewed 4k times. You create two different objects, both with Obj1 as their base - and then you ask them if they are instances of Obj1. Well, yes, they both are. AHM I see your reply is from many years ago, however I have never seen an approach using strict equality to directly compare JavaScript objects. While you would not normally compare an object to itself, this can be useful if you want to figure out which of object, out of a known set, you have a reference to.

Add a comment. Active Oldest Votes. The short version obj instanceof F looks to see if the object referenced by F. VLAZ Crowder T. Crowder k gold badges silver badges bronze badges. I'll have to go hunting I also meant to write a comment to notify you.

JavaScript instanceof operator is used for comparing object names with the desired object type for validating the actual object instance. All the objects are inherited from Object type class. This is a guide to JavaScript instanceof. Here we discuss an introduction to JavaScript instanceof with appropriate syntax, working and respective programming examples. You can also go through our other related articles to learn more —.

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