Class methods should utilize this JS-0105
Anti-pattern
If a class method does not use this, it can sometimes be made into a static function. If you do convert the method into a static function, instances of the class that call that particular method have to be converted to a static call as well (MyClass.callStaticMethod())
It's possible to have a class method which doesn't use this, such as:
class A {
constructor() {
this.a = "hi";
}
print() {
console.log(this.a);
}
sayHi() {
console.log("hi");
}
}
let a = new A();
a.sayHi(); // => "hi"
In the example above, the sayHi method doesn't use this, so we can make it a static method:
class A {
constructor() {
this.a = "hi";
}
print() {
console.log(this.a);
}
static sayHi() {
console.log("hi");
}
}
A.sayHi(); // => "hi"
Note : In the above examples that if you switch a method to a static method, instances of the class that call the static method (let a = new A(); a.sayHi();) have to be updated to being a static call (A.sayHi();) instead of having the instance of the class call the method
Bad Practice
class A {
foo() {
console.log("Hello World"); /*error Expected 'this' to be used by class method 'foo'.*/
}
}
Recommended
class A {
foo() {
this.bar = "Hello World"; // OK, this is used
}
}
class A {
constructor() {
// OK. constructor is exempt
}
}
class A {
static foo() {
// OK. static methods aren't expected to use this.
}
}