Code Example: Express REST API now includes x402

[sscovil]

We've added a working example of the x402 protocol to the EVMAuth TypeScript SDK + Express v5 code example:

evmauth-ts/examples/express/src/middleware.ts

Lines 37 to 55 in ac8a9f0

	if (routeConfig && authSigner !== null) {
	const payTo: Address = (await auth.wallet()) as Address;
	const route = req.path;
	const issueTokens: RequestHandler = async (
	_req: Request,
	_res: Response,
	_next: NextFunction
	): Promise<void> => {
	if (authSigner !== null) {
	await authSigner.issue(walletAddress, tokenId, amount);
	next();
	}
	};
	return paymentMiddleware(payTo, { [route]: routeConfig })(
	req,
	res,
	issueTokens as NextFunction
	);
	}

This enables end users to purchase EVMAuth tokens using ERC-20 tokens (e.g. USDC, USDT, PYUSD), via the ERC-3009 "Transfer With Authorization" standard.

There is currently just one minor quirk, which was reported to the x402 team. Despite that, it still works as expected.