Object Methods

Any value may be assigned to an object property, including a function.

A function that is assigned to a property of an object is referred to as a method.

Object methods can be created by assigning a function to a property when an object literal is created:

let dog = {
  speak : function() {
    return "woof woof";
  }
}

Methods can be assigned with dot notation:

let dog = {};

dog.speak = function() {
  return "woof woof";
}

Subscript notation can also be used:

let dog = {};

dog['speak'] = function() {
  return "woof woof";
}

Invocation

Invoking object methods has to be done through the name assigned to the object, in the form obj.methodName().

If the method is called without the preceding object name, you will get a Reference Error.

let dog = {};

dog.speak = function() {
  return "woof woof";
}

dog.speak();  // "woof woof"

Example

JS Object methods are similar to Java instance methods.

Just as you would create a new instance of a class in Java and invoke one if its methods, you can do the same with JS objects. The core difference is that unlike Java, you are not required to create a class definition to create an instance of an object. What's more, you can assign functions to the object and store them in properties dynamically.

let myObj = {};
myObj.makeArray = function(...args) {
  return args;
}

console.log(myObj.makeArray(1,5,2,34,1,67));

Skill Drill

1. Create a new object let myMath.
2. Assign myMath properties like add(num1,num2), subtract(num1,num2), multiply(num1,num2) and divide(num1,num2), which return the computed value of each operation.
3. Invoke each potential operation and ensure a result is returned.

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