Parameters and arguments

Learn the difference between parameters and arguments.

Parameters vs arguments

The names written in the parentheses of a function declaration are called parameters. The values supplied in the parentheses when the function is called are arguments. These two terms are often confused.

Example: in function greet(name) { ... }, name is a parameter. In the call greet("Alex"), "Alex" is an argument. A parameter is a placeholder; an argument is the actual value for that call.

Multiple parameters

A function can take more than one parameter; you separate them with commas. For example, function makeSentence(subject, verb, object) { ... } takes three parameters.

When calling it, you pass arguments in the same order, comma-separated: makeSentence("Cat", "chases", "mouse"). The first argument binds to the first parameter, the second to the second. This is called parameter binding.

Exercise Add two numbers

Define a function called addNumbers. It should take two parameters: a and b. Return the value a + b. Then print the result with console.log(addNumbers(7, 5)).

Show example solution

function addNumbers(a, b) {
  return a + b;
}

console.log(addNumbers(7, 5));

Test yourself

In the code below, what is '3'?
```
function mul(a, b) {
  return a * b;
}
mul(3, 4);
```
- Parameter
- Return value
- Argument
- Function name
Show answer

Argument — Correct. 3 is the value given at call time, so it is an argument.

Provide the right argument

function greet(name) {
  console.log("Hi " + name);
}
greet(____);

Show answer

function greet(name) {
  console.log("Hi " + name);
}
greet("Alex");

Match parameter and argument

function f(x)

x is a parameter
f(5)

5 is an argument
function g(a, b)

a, b are parameters
g(2, 3)

2, 3 are arguments

Next lesson: Function expressions

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