How can I safely check if an object exists in JavaScript?

General Discussions
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1

I know this works without error:

if (!null) alert(“GOT HERE”); But this throws an error when I try:

if (!maybeObject) alert(“GOT HERE”); because maybeObject is not defined. What’s the best way to do a JavaScript if exists check without causing errors?

2

I’ve been dealing with cross-browser quirks and shared scripts for years, and honestly, the most bulletproof way I’ve found is using typeof. It doesn’t throw errors even if the variable was never declared:

if (typeof maybeObject !== "undefined" && maybeObject) {
  alert("Object exists and is truthy");
}

This pattern has served me well in larger codebases where some variables might not always be loaded. It’s reliable for a safe javascript if exists check and plays nicely in mixed-scope situations.

3

Yeah, totally agree with Priyada. I’ve been working a lot with modern ES features, and if you’re in a newer codebase (ES2020+), optional chaining makes this even cleaner, especially when you’re checking deeper properties:

if (maybeObject?.property) {
  alert("Property exists");
}

No more nested checks or guards — this returns undefined silently if maybeObject is undefined, so no errors thrown. It’s a super intuitive way to do a javascript if exists check when working with nested or uncertain objects. Great for team projects where objects might come in partially shaped.

4

Building on that if you’re in one of those edge-case scenarios where the variable might not be declared at all (like from dynamic scripts or plugins), then I usually reach for a try-catch. I’ve seen this save entire debugging sessions:

try {
  if (maybeObject) {
    alert("Exists!");
  }
} catch (e) {
  alert("maybeObject is not defined");
}

It’s a last-resort kind of thing, but sometimes in browser dev or plugin-heavy environments, it’s the only way to make a javascript if exists check work without crashing your code. Think of it as a seatbelt for unpredictable contexts.