Apparently possible to create assertion functions through JSDoc

[voxpelli]

Just read this comment by @michaelfig in the jsdoctypeparser repo: jsdoctypeparser/jsdoctypeparser#50 (comment)

It mentions the possibility of making assertion functions:

/** @returns {asserts foo is Bar} */

I had no idea one could do this through JSDoc, I have so far always typed those functions using TypeScript definition files. Will surely try this out in future code, but wanted to share here right ahead so that I don't forget 👍

[voxpelli]

I can't get this to work fully though, the asserts foo is Bar part is recognized, but can't get it to actually accept a proper bool return value or a actually have any effect anywhere

[voxpelli]

Nevermind, got it to work:

/**
 * @param {any} value
 * @returns {value is Iterable<*>}
 */
const isIterable = (value) => Boolean(value && value[Symbol.iterator]);