Use a default parameter

Provide a fallback when the call supplies no argument.

Official sourceECMAScript — function parameter initializersReviewed: 2026-08-26

STEP 1 · LEARN

How it works

A parameter initializer is evaluated when the corresponding argument is missing or undefined. This gives the function a clear fallback without repeated checks in its body.

Correct example

function greet(name = 'vizitator') {
  console.log(`Salut, ${name}!`);
}

greet();

The call without an argument uses the “vizitator” default.

Common mistake

function greet(name) { console.log(`Salut, ${name}!`); }
greet();

Without an initializer, name becomes undefined and the message is not the intended one.

STEP 2 · APPLY

Your exercise

Declare greet with the default name “vizitator”, build the message and call the function without an argument.

script.jsJAVASCRIPT

Isolated consoleisolated

Preparing the runtime…

Run the code to see the result.

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STEP 4 · CHECK

What needs to pass

0%not checked

greet declares name with the vizitator default and is called without an argument.
The message includes name in a template literal.
The output is Salut, vizitator!.

Explain the solution logic

The parameter initializer supplies the value before the body builds the message.

How it works

Your exercise

Write and run the code

What needs to pass