The difference between arrow function and ordinary function

Reference resources ：https://juejin.cn/post/7050492355056664612

The arrow function doesn't [[Construct]]

2. The function object is a support [[Call]] 、 [[Construct]] Objects of internal methods . Every support [[Construct]] Object of must support [[Call]], in other words , Each constructor must be a function object . therefore , Constructors can also be constructor functions or constructor objects .
   therefore , Want to use... For an object new, You have to make sure that the object has [[Construct]] This internal approach . The arrow function does not [[Construct]].

Why does the arrow function not [[Construct]]

Arrow function at the beginning of design , To design a shorter function without binding this. So the arrow function is not a parameter super、this、new.target Define local binding . In the arrow function this、super、arguments And new.target These values are determined by the nearest non arrow function on the periphery .
The designer of such a function does not think it is necessary to delegate to a function that can [[Construct]] The objective function of , So the arrow function doesn't [[Construct]].
At the same time, there is no need to construct prototypes , So the arrow function doesn't exist prototype attribute .

The difference between arrow function and ordinary function

1. No, this、super、arguments And new.target binding ：this、super、arguments And new.target The value of is determined by the nearest non arrow function .
2. Can not be new call ： The arrow function doesn't [[Construct]] Method , Therefore, it cannot be used as a constructor , Use new Calling the arrow function will throw an error .
3. There is no prototype ： Since you can't use the arrow function new, Then he doesn't need a prototype , There is no prototype attribute .
4. Can't change this：this The value of cannot be modified inside the function , The value of a function remains constant throughout its life cycle .
5. No, arguments object ： The arrow function doesn't arguments binding , You must rely on named or remaining arguments to access the parameters of a function .
6. Duplicate named parameters are not allowed ： Arrow functions are not allowed to have duplicate named arguments , Whether or not in strict mode ： And relatively speaking , Traditional functions prohibit this repetition only in strict mode .