Throw and try/catch

[mhulse]

Use just throw and try/catch around awaits:

basic-node-module/index.js

Lines 51 to 65 in 5df8ced

	if (this.options.orange == 'orange') {
	// Instead of using `writeFile().then()`, use await:
	await fs.writeFile(html, 'Hello world!', 'utf8');
	let result = await fs.readFile(html, 'utf8');
	await fs.unlink(html);
	// Resolve this async function with the result:
	return result;
	} else {
	throw new Error(`Orange isn’t orange, it’s ${this.options.orange}!`);

Here's example of just throw:

https://github.com/mhulse/get-tile-url/blob/f79b35889e0ad43fda12053cd1d2a1dcd8ef3b61/index.js#L90

[mhulse]

https://github.com/i0natan/nodebestpractices#-22-use-only-the-built-in-error-object

[mhulse]

Great examples here:

https://github.com/sindresorhus/p-queue/blob/37c1204cc68e54f9d4ecf4e5200eb9313fd277be/index.js#L69-L79

[mhulse]

Good advice here: https://stackoverflow.com/a/52215925/922323

[mhulse]

This talks about how to use top-level caller:

https://stackoverflow.com/a/48685979/922323

[mhulse]

Sync way: https://stackoverflow.com/questions/30367395/how-to-catch-errors-in-synchronous-functions-in-node-js

[mhulse]

This is interesting:

https://makandracards.com/makandra/43653-javascript-don-t-throw-exceptions-from-async-functions

TLDR: A function is hard to use when it sometimes returns a promise and sometimes throws an exception. When writing an async function, prefer to signal failure by returning a rejected promise.

[mhulse]

I need to make a readme wiki repo on exception handling, just for my own education. This shit is probably one of the more complex/ambiguous feature(?) of es6+ (in my mind).

Just need more practice. :)

[mhulse]

Looks like thowing a new error will result in a rejected promise in a async/await.

https://stackoverflow.com/a/42453705/922323

[mhulse]

A few good paragraphs about constructors and async operations; basically, don't do that in constructor.

[mhulse]

Great tips here:

https://eloquentjavascript.net/08_error.html

Another way to set a breakpoint is to include a debugger statement (consisting of simply that keyword) in your program. If the developer tools of your browser are active, the program will pause whenever it reaches such a statement.

If you’re programming only for yourself, you can afford to just ignore such problems until they occur. But if you build something that is going to be used by anybody else, you usually want the program to do better than just crash. Sometimes the right thing to do is take the bad input in stride and continue running. In other cases, it is better to report to the user what went wrong and then give up. But in either situation, the program has to actively do something in response to the problem.

[mhulse]

https://medium.com/@xjamundx/custom-javascript-errors-in-es6-aa891b173f87

[mhulse]

Good tips here:

https://stackoverflow.com/a/42171508/922323

[mhulse]

Returning a promise from async will not double wrap the promise:

https://stackoverflow.com/a/35302535/922323

Non-promise return will be wrapped.

No return will return a promise.