We’re Already Assigning to this, So Why Return this in method chaining?

This always bugged me.

If I’m already setting stuff on this, like this.name = "Netaji",

the object is already updated. So why do we still return this at the end of the method?

Here’s what I mean:

class User {
  setName(name) {
    this.name = name;  // modifies the object
    return this;       // looks redundant, right?
  }

  setAge(age) {
    this.age = age;
    return this;
  }
}

const u = new User();
u.setName("Netaji").setAge(18);

At first, I thought return this was just some “fancy” coding thing.

But no — it’s actually about what the method call expression gives back.

Try this without returning anything:

class Demo {
  setX() { this.x = 10; }  // no return
}

const d = new Demo();
console.log(d.setX()); // undefined

Even though the object is changed, d.setX() itself returns undefined.

So if you try to chain like d.setX().setY(), boom — it breaks.

That’s the whole point. this updates the object. return this lets you keep using that same object in one smooth chain.

Example of working chaining:

const u = new User();
u.setName("Netaji").setAge(18);
console.log(u.name, u.age); // "Netaji", 18