How to check for an undefined or null variable in JavaScript? Update 2025 A more concise and commonly used approach nowadays: if (some_variable == null) { do stuff } Using == null checks both null and undefined, since == (loose equality) treats them as the same This is shorter and more readable than explicitly checking both cases
JS Check for Null – Null Checking in JavaScript Explained Let’s now see the two major ways you can check for null and how it relates to undefined How to Check for Null in JavaScript with Equality Operators The equality operators provide the best way to check for null You can either use the loose double equality operator (==) or the strict triple equality operator (===) How to use the loose
How to check for null, undefined or blank Variables in . . . Null was designed to represent the absence of an object or value, so it was given a special value of all zeros This made it easy for the language to check if a variable was null since it could simply check if the value was equal to zero Example: When checking for null variables in JavaScript, there are several standard approaches One of the
Loose null checks in JavaScript | The Trevor Harmon tl;dr: value == null is an easy way to capture both null and undefined in a equality check, and it's the one clear case that a loose equality check is better than a strict equality check By default, I always use strict equality checks when writing JavaScript
Is there a way to check for both `null` and `undefined`? Using a juggling-check, you can test both null and undefined in one hit: If you use a strict-check, it will only be true for values set to null and won't evaluate as true for undefined variables: You can try this with various values using this example: if (x == null) { console log(name + ' == null'); if (x === null) {
How to do your null-checks safely in JavaScript - Synergy Codes Learn how to perform null checks safely in JavaScript and TypeScript Understand the differences between ==, ===, and Object is to avoid runtime errors and handle null or undefined values effectively