JavaScript - run once without booleans

Question

Is there a way to run a piece of JavaScript code only ONCE, without using boolean flag variables to remember whether it has already been ran or not?

Spe

Answer 1

Elegant solution from Douglas Crockford, spent some time to understand how it works and stumbled upon this thread.

So the wrapper once return function which is just invokes parameter's function you passed. And taking advantage of closures this construction replaced passed function to empty function, or null in original source, after the first call, so all the next calls will be useless.

This is something very close to all other answers, but it is kinda self containing code and you could use it independently, which is good. I am still trying to grasp all the entire mechanism of replacement, but practically it just works perfectly.

function once (func) {

 return function () {
   var f = func;
   func = null;
   return f.apply(this, arguments);
 };

}

function hi(name) {
  console.log("Hi %s", name);
}

sayonce = once(hi);
sayonce("Vasya");
sayonce("Petya");

for those who are curious here is jsbin transformations