What is null javascript

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Actually I think you may need to use if value! In my situation, I just needed to check if the value is null and undefined and I did not want to filter 0 or false or '' values. This is a comment on WebWanderer's solution regarding checking for NaN I don't have enough rep yet to leave a formal comment. The solution reads as. A better test would be:. But as null is also an object we can detect it as a null.

I made a more complex function natureof witch will do better than typeof and can be told what types to include or keep grouped. The route is whatever chain of values that can blow up. Of course if you prefer you can use null or 'No value' Whatever suit your needs.

Usually a DOM query or a jQuery selector may throw an error if it's not found. But using something like:. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Collectives on Stack Overflow. Learn more. How do I check for null values in JavaScript? Ask Question. Asked 10 years, 8 months ago. Active 24 days ago.

Viewed 1. How can I check for null values in JavaScript? I wrote the code below but it didn't work. Improve this question. Are you sure the values you are testing are actually null and not just empty string? Check out my wording, I'm clearly making a general statement about the language in reference to the OP's practise, and not proposing that this solves his problem.

TRiG the proposed changes fundamentally alter the nature of the question to the point where the answers not just mine lose context and don't make sense. The edit should just be a comment. Show 2 more comments. Active Oldest Votes. I'm guessing you're actually looking for empty strings, in which case this simpler code will work: if!

Improve this answer. Matthias Braun Nobody Nobody It would be very useful to know which parts of this test for which values. Sometimes you're looking for one in particular.

Somewhat of a late statement, but yes, you can perform test against each one inorganik , see my answer below — WebWanderer. Readers, please be careful when using this type of test on numeric data. Do not use! The answer itself states this: " The same thing applies to JavaScript but JS is built in such a way that the string type is treated like primitive values. As I mentioned earlier, an object is a custom data type made out of multiple primitive data types or even other objects.

An array is a collection of other primitive types like a list of names, or a list of numbers. When you check the type of an array, you will see object:. Since each of the object is a custom type, a variable space is not enough to hold all the items and the configuration in it. The data items will be stored somewhere in the computer memory and the variable will only store the address to that memory location.

Now that we know there are two types in JavaScript, we can set the initial starting values of the primitive types like this:. To fully erase the object from the memory, we will have to assign null to that object.

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How do we use it?