String Concatenate

JWStringConcat joins two strings into one. a + b, no separator added, straight concatenation. It's the node you reach for when you're building something out of pieces - a filename, a path, a prompt assembled from parts.

The reason this shows up in real workflows is that useful strings are rarely a single literal. A save name might be a prefix plus a counter plus an extension. A prompt might be a shared base description plus a per-run trigger word. A path might be a folder plus a filename. Concat lets you keep each piece in its own node - editable, reusable - and stitch them at the end instead of hardcoding the whole thing in one box.

How it works

It sticks b onto the end of a and outputs the result. That's the literal behaviour - no space, no slash, no separator is inserted. "render_" + "0042" → "render_0042". If you want a separator, it goes in one of the strings: put the underscore at the end of a, or the slash inside the path piece. To chain more than two, feed the output of one JWStringConcat into the a of the next.

The inputs and outputs that matter

• a (STRING) - the first piece, default empty. Comes out on the left.
• b (STRING) - the second piece, default empty. Gets appended.
• Output: STRING - the two joined together.

Order matters here (unlike a min or add): a then b. Both are single-line string fields you can type into directly, or wire from other nodes - a JWString, a JWIntegerToString counter, a JWDatetimeString timestamp.

How to install it

Part of jamesWalker55/comfyui-various, a pack of small utility nodes.

• ComfyUI Manager: search "Various ComfyUI Nodes by Type", install, restart. Node came in red with someone's workflow? Install Missing Custom Nodes.
• Manually:

  cd ComfyUI/custom_nodes
  git clone https://github.com/jamesWalker55/comfyui-various
  

  Restart afterward. No models, no dependencies.

Under the jamesWalker55 category after restart.

Common issues

• My separator disappeared / everything ran together. It doesn't add one - that's by design. Bake the separator into one of the inputs: end a with _ or /, or use a small JWString holding just the separator as a middle piece in a chain.
• A number won't connect. Concat wants strings on both sides. Convert an integer with JWIntegerToString (great for zero-padded counters) or a float with JWFloatToString before wiring it in.
• I need three or more pieces. Chain the nodes - output of one into a of the next. It's a little verbose on canvas, but it keeps each piece independent.
• Node is red / missing. The pack isn't installed. Install via Manager or clone the repo, then restart.

The classic combo is JWIntegerToString → JWStringConcat for building sortable output names like frame_0001.png without touching a scripting node. Simple, and it just works.