I want to implement constants in a class
, because that's where it makes sense to locate them in the code.
So far, I have been implementing the following workaround with static methods:
class MyClass {
static constant1() { return 33; }
static constant2() { return 2; }
// ...
}
I know there is a possibility to fiddle with prototypes, but many recommend against this.
Is there a better way to implement constants in ES6 classes?
Here's a few things you could do:
Export a const
from the module. Depending on your use case, you could just:
export const constant1 = 33;
And import that from the module where necessary. Or, building on your static method idea, you could declare a static
get accessor:
const constant1 = 33,
constant2 = 2;
class Example {
static get constant1() {
return constant1;
}
static get constant2() {
return constant2;
}
}
That way, you won't need parenthesis:
const one = Example.constant1;
Then, as you say, since a class
is just syntactic sugar for a function you can just add a non-writable property like so:
class Example {
}
Object.defineProperty(Example, 'constant1', {
value: 33,
writable : false,
enumerable : true,
configurable : false
});
Example.constant1; // 33
Example.constant1 = 15; // TypeError
It may be nice if we could just do something like:
class Example {
static const constant1 = 33;
}
But unfortunately this class property syntax is only in an ES7 proposal, and even then it won't allow for adding const
to the property.