JSDoc is usually used to specify metadata for javascript code, and can be used to automatically generate documentation. See: https://jsdoc.app/about-getting-started.html

Example:

/**
 * @author Some Guy <example@example.com>
 * @see {@link https://jsdoc.app/tags-description.html} for further information.
 * @description How to use JSDoc to tag javascript.
 */

There is no official way to specify this. At least no One True Way.

With that said, the most widely accepted is JSDoc comments. You need to start a block comment with /** (two asterisks) and then you can use the special JSDoc syntax to explain your source with @author and @see:

/**
 * Function that returns a random number
 * @author Jon Skeet
 * @see {@link https://stackoverflow.com/a/11373465}
 * 
 * @param {number} min - minimum bound (inclusive)
 * @param {number} max - maximum bound (inclusive)
 * @return {string} - uniformly distributed integer within the range as a string 
 */
function rand(min, max){
   return (Math.floor(Math.random() * (max - min + 1)) + min).toFixed(0);
}

Maybe even machine readable?

JSDoc is machine readable. There are many tools that consume it. Most notably, many standard JavaScript editors like Visual Studio Code will give you the JSDoc for a function on hover.

However, there are other tools that can consume JSDoc or subset of it. They may produce documentation, or perform type checking based on what is specified for @param and @return, or other tasks.

It is also worth noting that you do not need to have any tool in order to use JSDoc. You can write it directly in your source code even if it does not get consumed ever. It can still be read by other humans who would understand it. Even if it is the first time they encounter the documentation style, it is straight-forward enough to be easily understood.