Is there a way to create interfaces in ES6 Node 4

Question

ES6 is fully available in Node 4  I was wondering whether it includes a concept of interface to define method contracts as in MyClass implements MyInterface    I can t find much with my Googling  but maybe there is a nice trick or workaround available

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there are packages that can simulate interfaces     you can use  es6-interface

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This is my solution for the problem  You can  implement  multiple interfaces by overriding one Interface with another   class MyInterface          Declare your JS doc in the Interface to make it acceable while writing the Class and for later inheritance                Gives the sum of the given Numbers         param  Number  a The first Number         param  Number  b The second Number         return  Number  The sum of the Numbers             sum a  b    this  WARNING  sum a  b                delcare a warning generator to notice if a method of the interface is not overridden        Needs the function name of the Interface method or any String that gives you a hint         WARNING fName  unknown method             console warn  WARNING  Function    fName    is not overridden in   this constructor name            class MultipleInterfaces extends MyInterface          this is used for  implement  multiple Interfaces at once                Gives the square of the given Number         param  Number  a The Number         return  Number  The square of the Numbers             square a    this  WARNING  square a          class MyCorrectUsedClass extends MyInterface          You can easy use the JS doc declared in the interface          inheritdoc        sum a  b            return a b          class MyIncorrectUsedClass extends MyInterface          not overriding the method sum a  b     class MyMultipleInterfacesClass extends MultipleInterfaces          nothing overriden to show  that it still works     let working   new MyCorrectUsedClass     let notWorking   new MyIncorrectUsedClass     let multipleInterfacesInstance   new MyMultipleInterfacesClass        TEST IT  console log  working sum 1  2      working sum 1  2       output   working sum 1  2    3   console log  notWorking sum 1  2      notWorking sum 1  2       output   notWorking sum 1  2    undefined     but also sends a warn to the console with  WARNING  Function  sum a  b   is not overridden in MyIncorrectUsedClass   console log  multipleInterfacesInstance sum 1  2      multipleInterfacesInstance sum 1  2       output   multipleInterfacesInstance sum 1  2    undefined     console warn   WARNING  Function  sum a  b   is not overridden in MyMultipleInterfacesClass   console log  multipleInterfacesInstance square 2      multipleInterfacesInstance square 2       output   multipleInterfacesInstance square 2    undefined     console warn   WARNING  Function  square a   is not overridden in MyMultipleInterfacesClass    EDIT   I improved the code so you now can simply use implement baseClass  interface1  interface2       in the extend         Implements any number of interfaces to a given class     param cls The class you want to use    param interfaces Any amount of interfaces separated by comma    return The class cls exteded with all methods of all implemented interfaces    function implement cls     interfaces        let clsPrototype   Object getPrototypeOf cls  prototype      for  let i   0  i  lt  interfaces length  i              let proto   interfaces i  prototype          for  let methodName of Object getOwnPropertyNames proto                 if  methodName     constructor                   if  typeof proto methodName       function                       if   clsPrototype methodName                             console warn  WARNING     methodName    of Interface    interfaces i  name    is not declared in class    cls name                               clsPrototype methodName    proto methodName                                             return cls        Basic Interface to warn  whenever an not overridden method is used class MyBaseInterface          declare a warning generator to notice if a method of the interface is not overridden        Needs the function name of the Interface method or any String that gives you a hint         WARNING fName  unknown method             console warn  WARNING  Function    fName    is not overridden in   this constructor name                create a custom class    This is the simplest example but you could also use       class MyCustomClass1 extends implement MyBaseInterface            foo    return 66              class MyCustomClass1 extends MyBaseInterface       foo    return 66         create a custom interface class MyCustomInterface1           Declare your JS doc in the Interface to make it acceable while writing the Class and for later inheritance                 Gives the sum of the given Numbers         param  Number  a The first Number         param  Number  b The second Number         return  Number  The sum of the Numbers             sum a  b    this  WARNING  sum a  b             and another custom interface class MyCustomInterface2                  Gives the square of the given Number         param  Number  a The Number         return  Number  The square of the Numbers             square a    this  WARNING  square a             Extend your custom class even more and implement the custom interfaces class AllInterfacesImplemented extends implement MyCustomClass1  MyCustomInterface1  MyCustomInterface2                   inheritdoc            sum a  b    return a b                   Multiplies two Numbers        param  Number  a The first Number        param  Number  b The second Number        return  Number             multiply a  b   return a b          TEST IT  let x   new AllInterfacesImplemented     console log  x foo       x foo       output   x foo     66   console log  x square 2      x square 2       output   x square 2    undefined    console warn   WARNING  Function  square a   is not overridden in AllInterfacesImplemented   console log  x sum 1  2      x sum 1  2       output   x sum 1  2    3   console log  x multiply 4  5      x multiply 4  5       output   x multiply 4  5    20

User · Answer

Flow allows interface specification  without having to convert your whole code base to TypeScript  Interfaces are a way of breaking dependencies  while stepping cautiously within existing code

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Given that ECMA is a  class-free  language  implementing classical composition doesn t - in my eyes - make a lot of sense  The danger is that  in so doing  you are effectively attempting to re-engineer the language  and  if one feels strongly about that  there are excellent holistic solutions such as the aforementioned TypeScript that mitigate reinventing the wheel   Now that isn t to say that composition is out of the question however in Plain Old JS   I researched this at length some time ago   The strongest candidate I have seen for handling composition within the object prototypal paradigm is stampit  which I now use across a wide range of projects   And  importantly  it adheres to a well articulated specification   more information on stamps here

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Interfaces are not part of the ES6 but classes are   If you really need them  you should look at TypeScript which support them

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In comments debiasej wrote the mentioned below article explains more about design patterns  based on interfaces  classes    http   loredanacirstea github io es6-design-patterns   Design patterns book in javascript may also be useful for you   http   addyosmani com resources essentialjsdesignpatterns book   Design pattern   classes   interface or multiple inheritance  An example of the factory pattern in ES6 JS  to run  node example js     use strict       Types js - Constructors used behind the scenes     A constructor for defining new cars class Car     constructor options       console log  Creating Car    n           some defaults     this doors   options doors    4      this state   options state     brand new       this color   options color     silver             A constructor for defining new trucks class Truck     constructor options       console log  Creating Truck    n        this state   options state     used       this wheelSize   options wheelSize     large       this color   options color     blue              FactoryExample js     Define a skeleton vehicle factory class VehicleFactory        Define the prototypes and utilities for this factory     Our default vehicleClass is Car VehicleFactory prototype vehicleClass   Car      Our Factory method for creating new Vehicle instances VehicleFactory prototype createVehicle   function   options        switch options vehicleType       case  car         this vehicleClass   Car        break      case  truck         this vehicleClass   Truck        break        defaults to VehicleFactory prototype vehicleClass  Car         return new this vehicleClass  options            Create an instance of our factory that makes cars var carFactory   new VehicleFactory    var car   carFactory createVehicle                vehicleType   car               color   yellow               doors  6          Test to confirm our car was created using the vehicleClass prototype Car     Outputs  true console log  car instanceof Car        Outputs  Car object of color  yellow   doors  6 in a  brand new  state console log  car     var movingTruck   carFactory createVehicle                          vehicleType   truck                         state   like new                         color   red                         wheelSize   small           Test to confirm our truck was created with the vehicleClass prototype Truck     Outputs  true console log  movingTruck instanceof Truck        Outputs  Truck object of color  red   a  like new  state    and a  small  wheelSize console log  movingTruck

[javascript] Is there a way to create interfaces in ES6 / Node 4?

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