How to document a function returned by a function using JSDoc

Question

I am using JSDoc for parameter documentation.

It is clear how to document the parameter types for many_prompts, but what is the right way to document the function it returns?

/**
 * @param {Number} - number of times to prompt
 * @return {Function(prompt{Number})} - the returned function
 */
function many_prompts(count) {
  return function(prompt) {
    for(var i=0; i < count; i++) alert(prompt);
  }
}


//Example of use:
var y  =many_prompts(3);
y('Hello World');

Solution 1

You can document the inner function and then reference it like so

/**
 * @param {Number} - number of times to prompt
 * @return {many_prompts~inner} - the returned function
 */
function many_prompts(count){
  /**
   * My inner function
   *
   * @param {object} prompt Some parameter
   */
  var inner = function(prompt){
    for(var i=0;i<count;i++) alert(prompt)
  };
  return inner;
}

Solution 2

This seems to be working for me.

 /**
 * @param {Number} count - number of times to prompt
 * @return {function(): void} - the returned function
 */
  manyPrompts(count) {
      /**
       * My inner function
       *
       * @param {object} prompt Some parameter
       */
      const inner = function(prompt) {
        for (let i=0; i < count; i++) {
          alert(prompt);
        };
      };
      return inner;
  }

Solution 3

The way I prefer:

/**
 * @param {number} count - number of times to prompt
 * @returns { (promt:string) => void } - the returned function
 */
  manyPrompts(count) {
      /**
       * My inner function
       *
       * @param {object} prompt Some parameter
       */
      const inner = function(prompt) {
        for (let i=0; i < count; i++) {
          alert(prompt);
        };
      };
      return inner;
  }

Comments

[Jack Allan]

Is there a way to do this for anonymous inner functions?

[SGD]

For JSDoc you would need some form of reference, I guess it depends on how the anonymous function is used. Do you have an example?

[Ben Creasy]

Is this documented anywhere officially? Can't find it.

[SGD]

Not in full depth I'm afraid. Did you try tagging your inner function with @function many_prompts~inner

[Lucretiel]

Is there a way to do this if you're using arrow functions? For instance: many_prompts = count => prompt => ...

[SGD]

I have never tried, theoretically it should work as it is semantically the same but the question is if the available parsers do support this already.

[Minh Nghĩa]

Is there any documentation for this?

[lance.dolan]

Yeah, is this standard or non standard?

[Trevor]

Works in VSCode

[Pang]

promt seems misspelt.

[Mike Harrison]

You also don't need the parentheses: @return {function: void} works

[Aaron Campbell]

This doesn't seem to be recognized by VS Code.

[Aaron Campbell]

This seems to work in VS Code, but doesn't pick up on the inner function documentation. :(