Chapter XXI · The `this` Keyword
apply
The `apply` method invokes a function with a specified `this` value and arguments passed as an array collection.
01 How It Works
Think of packing loose items into a box cargo container before handing it over to a station.
Identical to `call`, except arguments are bundled into an array rather than listed individually.
example.js
function sum(a, b) {
return a + b + this.extra;
}
sum.apply({ extra: 5 }, [10, 20]); // 351. Target a function reference.
2. Call `.apply(contextObj, [arrayArgs])`.
3. Function executes instantly with explicit bindings and array arguments.
02 Practical Example
Here is how you might see this concept applied in real-world code:
practical.js
const numbers = [5, 10, 15];
const max = Math.max.apply(null, numbers); // 15Key Takeaway
Use `apply` when arguments are already structured or collected inside an array.