Can we say this is an IIFE ?!?- In Javascript

Question

As you know in Javascript, it's very common to use the following expression as an IIFE (Immediately Invoked Function Expression) :

(function(){
  //code ...
})();

I'm wondering if we can say that the following expression is an IIFE (when no return value needed):

new function(){
 //code ...
}

Or

new function(global){
  //code..
}(this);

Even though it's an object . Thanks .

Answer :

[ Thanks to @le_m , @vol7ron and @Bergi , here is the short answer ] Can we say that he following expression is an IIFE (Immediately Invoked Function Expression) ?

new function(){
 //code ...
}

Or

new function(global){
  //code..
}(this);

The answer is NO. And what's that ? It's just an unnamed object with an anonymous constructor, so we're not talking about functions here (plain and simple).

Answer 1

Is new function(){ ... } an IIFE?

Now, IIFE stands for Immediately Invoked Function Expression. And a FunctionExpression is defined as follows:

function BindingIdentifierₒₚₜ ( FormalParameters ) { FunctionBody }

So, are we dealing with a function expression? Let's analyze your syntax:

"type": "ExpressionStatement",
"expression": {
    "type": "NewExpression",
    "callee": {
        "type": "FunctionExpression",
        "params": [],
        "body": {
           ...
    },
    "arguments": []
}

This shows us that your code is not a function expression, but it includes a function expression as a part of the NewExpression.

Is this expression immediately invoked? In a way, yes - see [[Construct]] invocation. The constructor function is immediately invoked.

Still, I wouldn't call the whole thing an IIFE as the outer expression is not a function expression. Some call this expression Immeditately Invoked Constructor or IIC instead (thanks to @vol7ron, @Bergi for pointing this out).