In JavaScript, How Can One Ascertain Whether A Variable Is Either ‘undefined’ Or ‘null’?

In JavaScript, you can use the typeof operator to check if a variable is either undefined or null. Here’s an example:

let variable;

if (typeof variable === "undefined") {
  console.log("Variable is undefined");
} else if (variable === null) {
  console.log("Variable is null");
} else {
  console.log("Variable has a value");
}

This code snippet first checks if the variable is undefined by using typeof variable === "undefined". If it is, it logs "Variable is undefined". If not, it moves to the next condition and checks if the variable is null by using variable === null. If it is, it logs "Variable is null". If neither condition matches, it means the variable has a value, and thus it logs "Variable has a value".

About the Author Rex

I'm a passionate tech blogger with an insatiable love for programming! From my early days tinkering with code, I've delved into web dev, mobile apps, and AI. Sharing insights and tutorials with the world is my joy, connecting me to a global community of like-minded tech enthusiasts. Python holds a special place in my heart, but I embrace all challenges. Constantly learning, I attend tech conferences, contribute to open-source projects, and engage in code review sessions. My ultimate goal is to inspire the next generation of developers and contribute positively to the ever-evolving tech landscape. Let's code together!