Salesforce JavaScript Developer Practice Exam

What will the output be when message.showMessage() is called in the context of: let message = { hello: 'Hello', names: ['Sue', 'Joe'], showMessage: function() { this.names.forEach(function(name) { console.log(this.hello + ' ' + name); }); } }?

1. Hello Sue

2. undefined Sue

3. undefined Joe

4. undefined Sue and undefined Joe

The correct answer is: undefined Sue and undefined Joe

In the given code snippet, the `showMessage` method calls `this.names.forEach`, which executes a callback function for each element in the `names` array. However, it's important to note how `this` behaves within that callback function. In JavaScript, the value of `this` inside a regular function (as opposed to an arrow function) does not refer to the object that invokes the method (`message` in this case). Instead, it refers to the global object or `undefined` in strict mode when the function is called in a different context, like the way it is within the `forEach` method. As a result, inside the callback of `forEach`, `this.hello` will not refer to `message.hello`. Instead, it will evaluate to `undefined`, leading to the output being `undefined` concatenated with each name. So, when "Sue" and "Joe" are iterated over, the output becomes: - For "Sue": `undefined Sue` - For "Joe": `undefined Joe` This leads to the conclusion that when `message.showMessage()` is invoked, the final output will be `undefined Sue` and `undefined Joe`, reflected accurately in the option indicating both outputs