How to check if object is null in javascript

For example:. In this example, the square variable is null therefore the if statement evaluates it to false and executes the statement in the else clause. In JavaScript, null is a primitive value, not an object. It turns out that this is a historical bug from the first version of JavaScript that may never be fixed. In JavaScript, you often call a function to get an object. And then you access the property of that object. In this example, we select an element with id save and access its classList property.

Hence, accessing the className property of the null value results in an error:. Often, we have to make some compromises. And there's nothing wrong with that. Especially, when you work within a team, sometimes disagreement arises.

But in the end, we have to make a decision. This doesn't mean we blind ourselves from other options. Quite the opposite, we do our best to seek other possible solutions and understand each implication. That's how we can make an informed decision.

Yup, I too can coin terms, just like Gwyneth Paltrow's conscious uncoupling. Maybe I should start a tech version of Goop What is Vanilla JavaScript A. Solving false positive with constructor check Testing empty check on other values Improve empty check for null and undefined B. Related Tidbits. If so, a simple comparison to null or undefined is to compare! The doSomething function will run only if object is neither null nor undefined.

However, if you first check that object! You can use eval to cast any type including string and be executed by javascript, here is eval documentation.

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. Asked 9 years, 3 months ago. Active 1 month ago. Viewed 96k times. Improve this question. Nick G. If it actually may have the string values "null" and "undefined" , then your method can't be any simpler. It does sometimes have the strings "null" or "undefined". Thanks for the confirmation. You can also use!! It converts the object to boolean and then inverts it again.

Look at this answer for a very good explanation. Add a comment. Active Oldest Votes. Improve this answer. John 11k 11 11 gold badges 82 82 silver badges bronze badges.

I like your answer because it's reusable and very readable. However, I just found a slightly more efficient way of doing the actual check.