Formdata.append("key", "value") is not working

Dealing with client-sided FormData mishaps

Not seeing your data at the gala? Here's how to Sherlock your way out:

1. Call on FormData.get(key) to check if "key" RSVP'd.
2. Use Array.from(formData) to know who else joined the party.
3. Like a detective, take a peek at Request Payload in your browser's Network tab.

Sending FormData via XMLHttpRequest

XMLHttpRequest is the good ol' horse-drawn carriage of data transport, helpful for:

1. Nostalgia and better visibility in browser logs.
2. Scoping FormData in transit via Chrome DevTools.
3. Great for sending FormData when modern fetch is on strike.

Ensuring server-side reception

Make sure your server-side is dancing to the same tune:

1. The server must be set to dance the multipart/form-data twist.
2. If you’re waltzing in PHP, access FormData through the $_POST variable.
3. In an AJAX tango, don't skip steps. Set processData: false and contentType: false.

Embracing modern FormData features

Get the most out of your browser’s recent FormData dance steps:

1. Set your sights on new FormData methods in Chrome 50+ and Firefox 39+.
2. Keep your browser updated to catch every new move.

Checking FormData before the grand reveal

Do a final sweep before making a grand entrance:

1. Add any last-minute guests to FormData before the big send-off.
2. Use a for...of loop to sneak a peek at the guest list.
3. Dance the FormData around in browser logs - everyone loves a preview!

Utilising FormData for diverse rumbas

AJAX, the Electric Slide

When adding FormData to AJAX boogie:

1. Use new FormData(this) in form event listeners to get everyone on the floor.
2. All your main moves should be set before the AJAX send.
3. The AJAX steps processData: false and contentType: false should be followed for smooth FormData sliding.

FormData & file inputs, the Cha-Cha Slide

When you're sending files in your FormData tango:

1. On the dance floor, catch $_FILES in PHP to access the floor-filling files.
2. Remember, FormData adds File objects, swinging the client-server exchange.

Server-side issues, Twist & Shout!

When your data isn't doing the twist correctly on the server, check:

1. On the server, look for $_POST['key'] amongst the dancers.
2. Check that your server-side DJ is set up to play FormData objects.

Spicing up your FormData dance card

Creating Nested Macarena

Creating nested moves in FormData:

1. Understand how your server interprets unique dance moves.
2. Prepare your nested moves for a standout performance.

The Tango with non-standard data types

When bringing non-standard partners like JSON or Blobs:

1. Make sure to lead them correctly so JSON, Blob or binary data flow smoothly.
2. If you’re feeling bold, declare your own Content-type, or let the browser lead the dance.

The Fetch Jive with FormData

Performing the fetch jive:

1. Let the fetch function lead the way with FormData - no need to request headers manually.
2. Begin with the right foot, usually a POST move, to send data.