Check if element exists in jQuery

Elements in the wild: Practical instances

In real-world development, you may face various encounters where element existence checks are vital:

1. Dynamic Content: Have you just appended new content? If so, don't forget to check if the new elements have successfully made it to the party.
2. Error Prevention: "Look before you leap" was clearly advice meant for developers! Check for element existence before potentially hazardous operations.
3. Selector Sharpness: Remember, we're hunting for classes with a . and IDs with a #.
4. Vanilla Flavours: If jQuery is off the menu, document.getElementById('elementId') and document.querySelector('#elementId') are your go-to specialties in vanilla JavaScript.

Diving deep with .length

The .length property does more than meets the eye:

• Truth or Dare: In JavaScript, .length is a game of "Truth or Dare". Any positive number is a truthy value; on the other hand, 0 dares to be falsy.
• Gotcha!: If there's no matching element in the DOM, .length instantly reports a 0, giving you immediate feedback.
• Count Dracula: Who's good with handling duplicate instances? It's none other than .length, counting the occurrences like Count Dracula counts his bats 🧛‍♂️!

The CSS Equation

Keeping in line with CSS notation simplifies element selection in jQuery:

• Seek out classes using a ..
• Hunt for IDs using a #.

Using advanced CSS selectors in vanilla JavaScript:

const num_elements = document.querySelectorAll('.some .complex #selector').length;
if (num_elements) {
  // "Eureka! Found some elements with the complex selector!"
}
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Dynamic content and .length: The Tango

Dealing with dynamic content? Here's what you need to know about dancing the .length tango:

• Curiosity and Timing: Always verify an element's existence after the DOM has been updated. Curiosity killed the cat, but satisfaction brought it back!
• Keeping Watch: For complex applications, consider employing mutation observers to stay updated about all DOM changes.

Pitfalls to avoid

Here are some common blunders:

• Mixing up your selectors. Remember, CSS is not just a styling tool!
• Checking for existence before the element has even had a chance to be added (It's like looking for the guests before sending the party invites).
• Forgetting that .length not only verifies, but also counts. So, it might shock you with higher values when multiple elements match the selector.