--description--

If a function is called, but an argument is not provided, then the parameter will be assigned the value of undefined. This can lead to unexpected results if the function is not designed to handle this case.

function favoriteAnimal(animal) {
  return animal + " is my favorite animal!"
}

console.log(favoriteAnimal()); // Output: undefined is my favorite animal!

In the example above, the function favoriteAnimal is called without an argument. The parameter animal is assigned the value of undefined, which is then concatenated with the string " is my favorite animal!".

If a value is not provided you can make use of default parameters. Default parameters allow you to assign a default value to a parameter if no value is provided when the function is called.

function favoriteAnimal(animal = 'Giant Panda') {
  return animal + " is my favorite animal!"
}

In the example above, the default value of the parameter animal is set to 'Giant Panda'. If the function favoriteAnimal is called without an argument, the parameter animal will be assigned the value 'Giant Panda'.

--questions--

--text--

How do default parameters in JavaScript functions enhance the behavior of functions like favoriteAnimal when called without any arguments?

--answers--

They cause the function to throw an error if no argument is provided.

They prevent the function from being called without the required number of arguments.

They ensure the function returns null to indicate that no argument was passed.

They allow the function to execute with a predefined value, avoiding undefined related issues.

--video-solution--

4