Does solc.loadRemoteVersion() download a new version of solc each time it is run? about solc-js

[cameel]

No, there's no caching of any kind. loadRemoteVersion() is a very simple function that makes a HTTP request and stores the obtained binary in memory, without ever writing it to disk:

solc-js/wrapper.ts

Lines 43 to 69 in d6fee85

	function loadRemoteVersion (versionString, callback) {
	const memoryStream = new MemoryStream(null, { readable: false });
	const url = `https://binaries.soliditylang.org/bin/soljson-${versionString}.js`;
	https.get(url, response => {
	if (response.statusCode !== 200) {
	callback(new Error(`Error retrieving binary: ${response.statusMessage}`));
	} else {
	response.pipe(memoryStream);
	response.on('end', () => {
	// Based on the require-from-string package.
	const soljson = new Module();
	soljson._compile(memoryStream.toString(), `soljson-${versionString}.js`);
	if (module.parent && module.parent.children) {
	// Make sure the module is plugged into the hierarchy correctly to have parent
	// properly garbage collected.
	module.parent.children.splice(module.parent.children.indexOf(soljson), 1);
	}
	callback(null, wrapper(soljson.exports));
	});
	}
	}).on('error', function (error) {
	callback(error);
	});
	}

Each time you execute it, it will download the binary again.

If you want to load multiple versions and manage them in some way, you have do it on your own. The loaded binary as a JS module is passed to the callback you provide. Then you can do whatever you want with it.

Running solcjs --version, I only see the newest version available:

Yes, this returns only the version of the current binary. And by "current" I mean the one that is stored in soljson.js on disk. solcjs is a simple command-line wrapper that mimics the interface of native solc.

It never downloads the compiler, neither via loadRemoteVersion() or otherwise. Latest binary is always included in the npm package and if you're using the repo directly, you can use downloadCurrentVersion.ts to download that binary. solcjs works with only one version at at time but you can freely swap the file on disk for something else between invocations.

[alexreyes]

Okay, thanks for the info! @cameel