Salesforce JavaScript Developer Practice Exam

What will be the output of the following code: const person = { name: 'Lydia' }; function sayHi(age) { return `${this.name} is ${age}`; } console.log(sayHi.call(person, 21)); console.log(sayHi.bind(person, 21));?

1. undefined is 21 Lydia is 21

2. function function

3. Lydia is 21 Lydia is 21

4. Lydia is 21 function

The correct answer is: Lydia is 21 function

The output of the provided code involves understanding how the call and bind methods work in JavaScript. When invoking `sayHi.call(person, 21)`, the call method is executed with `person` as the context (value of `this`). Therefore, `this.name` refers to `person.name`, which is 'Lydia'. The function returns the string `'Lydia is 21'`, which gets printed to the console. In the second console log, `sayHi.bind(person, 21)` is called. The bind method does not execute the function immediately; rather, it creates and returns a new function. This new function, when called, will have `this` set to `person` and the first argument set to `21`. Since the current log statement is just referencing the function returned by bind, it outputs the text "function" instead of executing it. Thus, combining both outputs, the final output is `Lydia is 21` followed by `function`, which is why that particular choice reflects the behavior of the code accurately.