node.js捕获闭包变量

Question

I'm working on a simple debug function that evaluates a closure and gets all the relevant variables names in node.js. It should work at runtime. So, is there a way to automatically capture all the variable names in a closure? For example, is it possible to know the existence of "b", "c" and "d" variables in the following case?

var d=3;
function a(c){ 
   var b = true;
   eval( debug(/* need to access in runtime something like ["b","c","d"] */) );

}
function debug(vars){ 
   var txt = "";
   for(var i=0; i<vars.length; loop++){
      txt+="console.log('"+vars[i]+":' + " vars[i] + ");"
   }
   return txt
}

I could use brute force to scan a.toString() searching for all the "var " and for all the arguments parameters, but is there a native function to find it or a special variable (something like callee. vars ) to find the variables names in the closure?

I know "eval" is a big no, but I'm only using that at development environment.

Answer 1

Yes there is. Just return a function to close over c and set another var to that closure. Like this.

 function a(c){ var b = true; return function () { console.log(c); }; } var d = a(false); // undefined d(); // false