functions and methods

JS Function vs Method

Function

• Standalone, not attached to objects

• Called directly by name: calculateTotal()

• Defined with function declaration or expression

// Function example
function calculateTotal(items) {
  // ...
}

const calculateTotal = function(items) {
  // ...
};

Method

• Function attached to an object or class

• Called through object reference: object.doSomething()

• this keyword refers to the containing object

// Method example
const cart = {
  items: [],
  addItem(item) {
    this.items.push(item); // `this` refers to `cart`
  }
};

class Cart {
  constructor() {
    this.items = [];
  }
  addItem(item) {
    this.items.push(item); // `this` refers to the instance
  }
}

References

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