rlidwka / node-hotswap Goto Github PK

My web application is written in TypeScript. Hotswap is used to swap out the generated JS on the app server. If I generate source maps as well as JS, it looks like Hotswap attempts to read/compile the source map files.

I've played with the configuration but couldn't work out a way to exclude ".js.map" files from hotswap.

Could I be doing something odd in my imports/requires to trigger this behaviour?

Example stack trace:

debugger listening on port 5858
NODE_ENV: development

/Users/laurence/digitalstack/generated/server/models/db/AccessToken.js.map:1
ction (exports, require, module, __filename, __dirname) { {"version":3,"file":
                                                                    ^
SyntaxError: Unexpected token :
    at Module._compile (module.js:439:25)
    at extension_js (/Users/laurence/digitalstack/node_modules/hotswap/hotswap.js:220:10)
    at Module.load (module.js:356:32)
    at Function.Module._load (module.js:312:12)
    at Module.require (module.js:364:17)
    at require (module.js:380:17)
    at module.exports.Sequelize.import (/Users/laurence/digitalstack/node_modules/sequelize/lib/sequelize.js:621:63)
    at /Users/laurence/digitalstack/generated/server/models/db/index.js:29:44
    at Array.forEach (native)
    at new DbContainer (/Users/laurence/digitalstack/generated/server/models/db/index.js:28:14)
    at Object.<anonymous> (/Users/laurence/digitalstack/generated/server/models/db/index.js:43:10)
    at Module._compile (module.js:456:26)
    at extension_js (/Users/laurence/digitalstack/node_modules/hotswap/hotswap.js:220:10)
    at Module.load (module.js:356:32)
    at Function.Module._load (module.js:312:12)
    at Module.require (module.js:364:17)

Like ts-node.

node version: v10.14.0
express
my router.js:
const a = require('../api/test.js');
router.get('/', (req, res, next) => new a(req, res, next).main() );
my test.js
module.change_code = 1;
class test {
constructor(req, res, next) {
this.req = req;
this.res = res;
// super(req, res, next);
}
main() {
const b = {
a: 1,
b: 2
}
this.res.render('index', { title: 'Express11' , ...b})
}
}
module.exports = test;

I tried to enable hotswap for every module (patching it), to see if it works in a real project.

I didn't test the reloading. Just tried to run it.

The app died with undefined is not a function somewhere deep in the modules (under node_modules).

I tried to move require('hotswap') lower in the code, to exclude some modules, so the server actually started running, but then there was another error of the same kind.

To give a glimpse of what's happening:

undefined is not a function

   at Object.<anonymous> (/js/javascript-nodejs/node_modules/image-size/lib/detector.js:7:7)
   at Module._compile (module.js:460:26)
   at extension_js (/js/javascript-nodejs/node_modules/hotswap/hotswap.js:220:10)
   at Module.load (module.js:355:32)
   at Function.Module._load (module.js:310:12)
   at Module.require (module.js:365:17)
   at require (module.js:384:17)
   at Object.<anonymous> (/js/javascript-nodejs/node_modules/image-size/lib/index.js:7:16)

And here I paste the code from the image-size module (from npm):

'use strict';

var typeMap = {};
var types = require('./types');

// load all available handlers
types.forEach(function (type) {
  typeMap[type] = require('./types/' + type).detect;
});

module.exports = function (buffer, filepath) {
  var type, result;
  for (type in typeMap) {
    result = typeMap[type](buffer, filepath);
    if (result) {
      return type;
    }
  }
};

Looks like the reason why doesn't work is types being an array.

Occasionally, module._compile [line 221] throws a syntax error and crashes the app.
This happens when the watched file is streamed to disk.

I suggest to wrap the module._compile calls in a try-catch-block and emit an event if it fails.

The example on the read me only returns the following:

{ version: 0, prototype: undefined }
{ wow: 'thats working', prototype: undefined }

This module has been super helpful for me - thank you.

For my use case, I wanted to check each hotswapped file for syntax errors before requiring it. I implemented this here.

Would folks be interested in integrating this feature? Shall I make a PR?

Please see the project I've set up to reproduce the problem, here:
https://github.com/laurence-myers/hotswap-export-issue

(The project is written in TypeScript, but the JavaScript output is located in the "dist" directory.)

When "module.change_code = 1" is present in the module, a singleton instance, exported as "module.exports", will lose its inheritance chain.

This affects files using ES6 classes and inheritance. When using a custom extends function (like when targeting ES5), it works okay.

In TypeScript, using the syntax "export default instance;" will also fix the problem; presumably, this is because it actually generates the export like "module.exports = { default: instance };".