and I've tried to make it fairly syntax-neutral, so:
Hex can be written as $FE 0xFE, binary as %101010 or 0b10101
Better add FEH and 101010B too.

Good point, though I must admit FEH is horrible to parse as it can appear ambiguous (for instance: A5H and ASH, visually similar, or BAH - is that a ...

Also, what output format can the assembler produce? An o65 file is essential for relocation of binaries at load time.it has been mentioned here already that separate link stage is desirable which would require a linkable file format.

It's not a goal (at present) to generate relocatable binaries ...

Tuna, your project is very cool. Given your ambitions for compatibility with common assemblers, it could be very cool to see it on the command line (via node, deno, whatever). Another neat capability would be load/save from github (or other web-scm) repositories. If you don't want to just go on and ...

The Web Standards Consortium are currently in the middle of trying to establish a new file access api, to allow browsers to have consistent and secure access to user files - unfortunately, Firefox and Safari are struggling to keep up with the changes in standards, so writing for them involves using ...

That sounds like a pretty good goal. One idea would be to look at the macro systems in other assemblers and settle on implementing just the pieces you like. The x86 assembler NASM has a pretty good macro system you may want to check out. I think it would be one of the easier systems to implement ...

Unfortunately both Safari and Firefox are somewhat behind the curve at the moment...
Behind whose curve?

The Web Standards Consortium are currently in the middle of trying to establish a new file access api, to allow browsers to have consistent and secure access to user files - unfortunately ...

Hopefully it will keep doing passes until all the phase errors are taken care of. Normally two is enough; but I had a situation about 20 years ago where a chain of forward references required dozens of passes. Today's PCs are fast enough that it's not a problem.
It keeps on running passes until ...

Any chance you could make it browser-agnostic? Lots of people don't use Microsoft stuff, and as for Chrome and the company that pushes it...

Unfortunately both Safari and Firefox are somewhat behind the curve at the moment, and my primary focus is to get the functionality first. There is nothing ...

I've been developing my own browser based IDE for the 6502/65C02 (here, requires Chrome/Edge: https://feertech.com/legion/cerberus.html )

The assembler I've written is a basic multipass assembler, and I've tried to make it fairly syntax neutral, so:

.BYTE and DB are synonyms, as are '=' and EQU ...

Hi, I'm Andy,

I've been developing a browser based 6502/65C02 IDE in order to emulate the Cerberus2080 8-Bit Micro (https://www.thebyteattic.com/p/cerberus-2080.html)

It includes a cycle exact 65C02 emulator, syntax highlighting editor, multi-pass assembler, disassembler and debugger, as well as ...