JS: Class Expression

Class can be created by expression form:

• const x = class {body};
• const x = class name {body};

Class expression returns a value. Can be called inline like Immediately Invoked Function Expression.

// class is a expression. it returns a value. can be called inline
console.log(
 new class CC {
  constructor(x) {
   this.pp = x;
  }
 }(3),
);
// CC { pp: 3 }

Name optional

when assigned to a variable

varname = class class_syntax_name {body};

The class_syntax_name is optional. The varname is the constructor name.

When class_syntax_name is given, it is available inside the class body. and class_syntax_name is the tttttttt xxxxxxxx

both varname class_syntax_name are available inside to class body.

// the name of a named class expression is only available inside the class body

const Burger = class Sammy {
 constructor(x) {
  this.meat = x;
 }
};

try {
 new Sammy(3);
} catch (xerror) {
 console.log(xerror);
}
// ReferenceError: Sammy is not defined

const myburger = new Burger("beef");
console.log(myburger);
// Sammy { meat: "beef" }

/* in
varname = class class_syntax_name {body};
both class_syntax_name and varname are available in class body.
but both refers to the same constructor.
 */

const Burger = class Sammy {
 constructor() {
  console.log(Burger);
  console.log(Sammy);
 }
};

const myburger = new Burger();
console.log(myburger);
// prints
// [class Sammy]
// [class Sammy]

// returns
// Sammy {}