Google Closure Compiler's @param annotation is used to document variable parameters in functions

Question

Google Closure Compiler's @param annotation is used to document variable parameters in functions

I recently encountered an issue with a function that can accept a variable number of parameters.

After consulting the Google Closure Compiler wiki, I attempted to annotate the parameters using the @param annotation as suggested.

/**
 * Takes 2 or more strings and do something cool with them.
 * @param {...string} var_args
 * @return {string} the processed result
 */
function doSomethingCool() {
    var len = arguments.length;
    if (len < 2) {
        throw Error('Need at least 2 arguments');
    }

    ...
}

Issue

Upon compiling, a warning appeared stating:

JSC_INEXISTENT_PARAM: parameter var_args does not appear in doSomethingCool's parameter list at line 6 character 1

I tried using @param {string} arguments, but encountered the same error.

Even attempting @param {string} without specifying a variable name resulted in:

JSC_TYPE_PARSE_ERROR: Bad type annotation. expecting a variable name in a @param tag.

Inquiry

What went wrong in my annotation attempts and how should variable parameters be annotated for the Closure Compiler?

javascript annotations google-closure-compiler jsdoc

Answer 1

Answer №1

The error message is indicating that your var_args needs to be included in the parameter list.

/**
 * To do something cool with 2 or more strings.
 * @param {...string} var_args
 * @return {string} the processed result
 */
function doSomethingCool(var_args) {}

During compilation, Closure-compiler will recognize that it's not referenced and remove it.

If you prefer not to have it listed in the parameter list, you can use a @type annotation instead:

/**
 * To do something cool with 2 or more strings.
 * @type {function(...string):string}
 */
function doSomethingCool() {}

For accurate type checking, annotate the function to expect 2 or more strings:

/**
 * To do something unique with 2 or more strings.
 * @type {function(string, string, ...string):string}
 */
function doSomethingCool() {}

Answer 2

The error message is indicating that your var_args needs to be included in the parameter list.

/**
 * To do something cool with 2 or more strings.
 * @param {...string} var_args
 * @return {string} the processed result
 */
function doSomethingCool(var_args) {}

During compilation, Closure-compiler will recognize that it's not referenced and remove it.

If you prefer not to have it listed in the parameter list, you can use a @type annotation instead:

/**
 * To do something cool with 2 or more strings.
 * @type {function(...string):string}
 */
function doSomethingCool() {}

For accurate type checking, annotate the function to expect 2 or more strings:

/**
 * To do something unique with 2 or more strings.
 * @type {function(string, string, ...string):string}
 */
function doSomethingCool() {}

Google Closure Compiler's @param annotation is used to document variable parameters in functions

Issue

Inquiry

Answer №1

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