The case for Weak Dependencies in JS

Earlier today, I was briefly entertaining the idea of writing a library to wrap and enhance querySelectorAll in certain ways. I thought I’d rather not introduce a Parsel dependency out of the box, but only use it to parse selectors properly when it’s available, and use more crude regex when it’s not (which would cover most use cases for what I wanted to do).

In the olden days, where every library introduced a global, I could just do:

if (window.Parsel) {
	let ast = Parsel.parse();
	// rewrite selector properly, with AST
else {
	// crude regex replace

However, with ESM, there doesn’t seem to be a way to detect whether a module is imported, without actually importing it yourself.

I tweeted about this…

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In defense of reinventing wheels

One of the first things a software engineer learns is “don’t reinvent the wheel”. If something is already made, use that instead of writing your own. “Stand on the shoulders of giants, they know what they’re doing better than you”. Writing your own tools and libraries, even when one already exists, is labelled “NIH syndrome”  and is considered quite bad.