* Determine whether the given `value` is `null` or `undefined`. Here’s a sample function that you may copy to your project and is it to check for empty values: /** You can create a utility method checking whether a given input is null and undefined. Retrieve the List of Supported Hash Algorithmsĭetect Null or Undefined Values in JavaScript

Join an Array of Strings to a Single String Value Sort an Array of Objects in JavaScript, TypeScript or Node.jsĬheck If a Value Is an Array in JavaScript or Node.js Sort an Array of Strings in JavaScript, TypeScript or Node.js How to Reverse an Array in JavaScript and Node.js Retrieve a Random Item From an Array in JavaScript or Node.js How to Exit, Stop, or Break an Array#forEach Loop in JavaScript or Node.js How to Get an Index in a for…of Loop in JavaScript and Node.js Split an Array Into Smaller Array Chunks in JavaScript and Node.js How to Exit and Stop a for Loop in JavaScript and Node.js Sort a Boolean Array in JavaScript, TypeScript, or Node.jsĬheck If an Array Contains a Given Value in JavaScript or Node.jsĪdd an Item to the Beginning of an Array in JavaScript or Node.jsĪppend an Item at the End of an Array in JavaScript or Node.js Sort an Array of Integers in JavaScript and Node.js Get an Array With Unique Values (Delete Duplicates) b is defined as a null-value.How to Run an Asynchronous Function in Array.map()Ĭlone/Copy an Array in JavaScript and Node.js The difference between the two is perhaps a bit more clear through code: let a Ĭonsole.log(a) // undefined let b = null Ī is undefined - it's not assigned to anything, and there's no clear definition as to what it really is. null is a variable that is defined but is missing a value.undefined is a variable that refers to something that doesn't exist, and the variable isn't defined to be anything.Though, there is a difference between them: Undefined and null variables often go hand-in-hand, and some use the terms interchangeably. In this short guide, we'll take a look at how to check if a variable is undefined or null in JavaScript. Whether we lose a reference through side-effects, forget to assign a reference variable to an object in memory, or we get an empty response from another resource, database or API - we have to deal with undefined and null values all the time. Undefined and null values sneak their way into code flow all the time.

Javascript check if undefined