javascript - Dynamic type discovery in Google Closure Compiler -

i run situation have javascript object of unknown type. perform type check in script , call appropriate functions depending on detected type. e.g. this

/**  * @param {!array} aarray array  */ function actonarray(aarray) {  }  /**  * @param {*} aobject arbitrary object  */  function dosomething(aobject) {   // make sure have array   if ((null != aobject) && array.isarray(aobject)) {     actonarray(aobject);   } } 

running sniplet via advanced compilation in google closure compiler yields following warning message:

jsc_type_mismatch: actual parameter 1 of actonarray not match formal parameter found   : * required: array @ line 14 character 15     actonarray(aobject); 

this warning makes sense, since compiler not know semantic of type check.

my question is: how can annotate code tell compiler @ point have gained information type. in example tell inside if block know sure aobject parameter of type !array.

for patterns, compiler can automatically tighten types within tests:

// ==closurecompiler== // @compilation_level advanced_optimizations // @output_file_name default.js // @warning_level verbose // ==/closurecompiler==   /** @param {*} data */ function log(data) {   if (data && data instanceof array) {     logarray(data);   } else {     console.log(data);   } }  /** @param {!array} data */ function logarray(data) {   for(var = 0; < data.length; i++) {     log(data[i]);   } }  log([1, 2, 3]); 

however, in many cases cannot. in instances need type cast:

actonarray(/** @type {!array} */ (aobject)); 

note parenthesis - required