Green’s Dictionary of Slang

one who is out of work; by. ext., an idler.

1934		S. Beckett More Pricks than Kicks 57: The eyes of them all, the dockers, the railwaymen and, most terrible of all, the joxers, were upon him.
2006		‘Benjamin Black’ [John Banville] Christine Falls 249: [H]ow much better was he than the joxer scratching his balls over the racing pages.