for..in goes through all enumerable properties of the object and up its prototype chain. However, regular methods within a class are not counted as enumerable:
class MyClass {
myMethod() {
return {
test: 'true'
};
}
}
console.log(Object.getOwnPropertyDescriptor(MyClass.prototype, 'myMethod').enumerable);
This means they won't be included in iterations. If you need to loop over non-enumerable properties as well, you can utilize Object.getOwnPropertyNames (which loops over the object's own property names, requiring recursive execution for fetching all property names throughout the prototype chain):
const recurseLog = obj => {
for (const name of Object.getOwnPropertyNames(obj)) {
console.log(name);
}
const proto = Object.getPrototypeOf(obj);
if (proto !== Object.prototype) recurseLog(proto);
};
class MyClass {
dataA = 0;
dataB = 123;
constructor() {
recurseLog(this);
}
myMethod() {
return {
test: 'true'
};
}
}
const myInst = new MyClass();
You also have the option of making the method enumerable:
class MyClass {
dataA = 0;
dataB = 123;
constructor() {
for (const propOrMethod in this) {
console.log({propOrMethod})
}
}
myMethod() {
return {
test: 'true'
};
}
}
Object.defineProperty(MyClass.prototype, 'myMethod', { enumerable: true, value: MyClass.prototype.myMethod });
const myInst = new MyClass();
Alternatively, you can assign the method post-class declaration:
class MyClass {
dataA = 0;
dataB = 123;
constructor() {
for (const propOrMethod in this) {
console.log({propOrMethod})
}
}
}
MyClass.prototype.myMethod = () => ({ test: 'true' });
const myInst = new MyClass();
Or set it to the instance within the constructor:
class MyClass {
dataA = 0;
dataB = 123;
constructor() {
this.myMethod = this.myMethod;
for (const propOrMethod in this) {
console.log({propOrMethod})
}
}
myMethod() {
return {
test: 'true'
};
}
}
const myInst = new MyClass();