How can I determine if a variable is "undefined" or "null"?

📝**(Title)**: The Great Variable Hunt: Is it 'undefined' or 'null'? Here's how to find out!

👋**(Introduction)**: Hey there, fellow tech enthusiasts! 👋 Today, we're going on a wild adventure through the coding jungle to answer a burning question: "How can I determine if a variable is 'undefined' or 'null'?" 🕵️‍♂️ In this blog post, we'll tackle this problem head-on, providing easy solutions and unraveling the mystery behind those elusive coding creatures. So grab your magnifying glass, and let's get started! 🔍

🕵️**(Problem)**: Our brave coder here encountered a perplexing issue in their code snippet. They tried to determine if a variable named EmpName is 'undefined' with an if statement. However, instead of getting an answer, they stumbled upon a roadblock. The JavaScript interpreter decided to take a break and halt execution. 😱

🤔**(Explanation)**: To comprehend this hiccup, let's delve into the difference between 'undefined' and 'null'. When a variable is 'undefined', it means it has been declared but hasn't been assigned a value or hasn't existed within the scope of the code. On the other hand, 'null' is an assignment value that represents no value or an empty object pointer. It's like saying, "Hey, there's something but it's empty."

In our code snippet, the issue lies within the comparison. When verifying if a variable is 'undefined', we don't enclose it in quotation marks. By doing so, JavaScript assumes it's a string containing the word "undefined," and also a truthy value 🙃. Hence, the interpreter gets confused, leading to the unruly halt.

💡**(Solution)**: Fear not, intrepid coders, for we have the solution to tame this wild variable conundrum! Here are the corrected code snippets for both JavaScript and HTML:

JavaScript:

var EmpName = $("div#esd-names div#name").attr('class');
if (typeof EmpName === 'undefined') {
  // DO SOMETHING
};

HTML:

<div id="esd-names">
  <div id="name"></div>
</div>

In this revised code, we utilize the typeof operator to check if the variable EmpName is truly 'undefined'. If it is, then you can proceed with your fantastic "DO SOMETHING" action.

📣**(Call-to-Action)**: Now that you've conquered the mystical realm of checking variable existence, it's time to put your newfound knowledge into practice! 🎉 Share your thoughts, experiences, or any further questions in the comments section below. Don't forget to spread the word by sharing this blog post with your fellow code adventurers! Let's support and uplift one another in our coding journeys. Happy coding! 💻💪

So, what are you waiting for? Get out there and tame those undefined and null variable beasts! 🦁🦊🐯