检查包装器函数是否被调用？

Question

I have this code:

function Q(a){
  function cElems(e,f,p){var l=e.length,i=0;if(e instanceof Array){while(i<l){f(e[i],p);i++}}else{f(e,p)}}
  if(typeof a=="string"){
    var b=a[0],c=a.substr(1),r=[].slice.call(document.getElementsByClassName(c));
    return{
      setClass:function(b){cElems(r,function(e,p){e.className=p},b)}
    };
  }
}

I want to check if a wrapped function is called, ie: Q(".test").setClass("test2") , and return something different if not, like so:

if(wrapped==true){
  return{
    setClass:function(b){cElems(r,function(e,p){e.className=p},b)}
  };
}else{
  return "no constructor was called";
}

Is this possible?

Answer 1

In Q(..).x() , Q(..) is always invoked prior to x being resolved (and invoked); this can be clearly seen with rewriting it as so:

var y = Q(..);  // this executes and the value is assigned to y
y.x();          // and then the method is invoked upon the object named by y

Thus it is not possible to alter the already-executed behavior of Q(..) based on the result of invoking Q(..).x - the object has already been returned from Q(..) .

Answer 2

You can see if a function has been invoked, like so:

var costructoed = 0;
function Constructo(){
  constructoed = 1;
}
function whatever(func){
  if(constructoed){
    func('It worked!');
  }
  else{
    func('Constructo was not executed');
  }
}
whatever(console.log);
Constructo();
whatever(console.log);

To see whether a method in an Constructor has executed it's like:

function Constructo(){
  this.someValue = 0;
  this.someMethod = function(){
    this.someValue = 1;
  }
  this.someMethodWasExecuted = function(func){
    if(this.someValue === 1){
      console.log('someMethod was executed');
    }
    else{
      func();
    }
  }
}
function whenDone(){
  console.log('someMethod was not Executed whenDone ran instead');
}
var whatever = new Constructo;
console.log(whatever.someMethodWasExecuted(whenDode));
whatever.someMethod();
console.log(whatever.someMethodWasExecuted(whenDode));