ES6 - 在类中调用静态方法

Question

I have this class which does an internal call to a static method:

export class GeneralHelper extends BaseHelper{
     static is(env){
          return config.get('env:name') === env;
     }

     static isProd(){
         return GeneralHelper.is('prod');
     }
 }

Are there any keywords I can use to replace the class name in the line below:

GeneralHelper.is('prod');

In PHP there are self , static etc. Does ES6 provide anything similar to these?

TY.

Answer 1

If you are calling the static function from inside an instance, the right way to refer to the static function of the class is:

this.constructor.functionName();

Call static methods from regular ES6 class methods

Answer 2

It's the same as calling a method on an ordinary object . If you call the GeneralHelper.isProd() method, the GeneralHelper will be available as this in the method, so you can use

class GeneralHelper {
     static is(env) { … }
     static isProd(){
         return this.is('prod');
     }
}

This will however not work when the method is passed around as a callback function, just as usual . Also, it might be different from accessing GeneralHelper explicitly when someone inherits isProd from your class and overwrites is , InheritedHelper.isProd() will produce other results.

If you're looking to call static methods from instance methods, see here . Also notice that a class which only defines static methods is an oddball, you may want to use a plain object instead.

Answer 3

Both of the answers here are correct and good, but I wanted to throw in an added detail based on this question title.

When I saw "ES6 - Call static method within a class" it sounded like "call a static method (from a non-static method) within a class". Def not what the initial question asker is asking in the details.

But for anyone who wants to know how to call a static method from a non-static method within a class you can do it like this:

class MyClass {
    myNonStaticMethod () {
        console.log("I'm not static.")
        MyClass.myStaticMethod()
    }

    static myStaticMethod () {
        console.log("hey, I'm static!")
    }
}

MyClass.myStaticMethod() // will log "hey, I'm static!"

const me = new MyClass()

me.myNonStaticMethod() // will log "I'm not static" and then "hey, I'm static!"

The idea is that the static method is can be called without creating a new instance of the class. That means you can call it inside of a instance's method the same way you'd call it outside of the instance.

Again, I know that's not what the detail of the question was asking for, but this could be helpful other people.