New.target (ES6)

Today accidentally saw a lexical new.target!

What's this thing? In my mind, the new heel is a constructor! What the hell is this?

Let F = function f () {    if (!new. Target)      throw new Error (' ... ')    //  };  

Check it out and find out what it does is get the target constructor for the current new

You can guarantee that a function is used as a constructor, not just undefined.

Before, you wanted to make sure that the function was new instead of being called directly, maybe that would do it.

Let F = function f () {    if (!) ( This instanceof A))       throw new Error (' ... ');    // ···  };

But a guy with a B-grid can still write that.

Let F = f.apply (Object.create (F.prototype), [])

In ES6, class has checked for you (whether it's new).

New.target will know which class is currently under output F2

Class F2 extends f{  constructor () {    //' F2 '    console.log (new. target.name);}  }

Very unpopular compatibility is pretty miserable. Chrome Firefox 41

You know, that's fine.

New.target (ES6)