A parameter is a named variable passed into a function. Parameter variables are used to import arguments into functions.

For example:

function example(parameter) {
  console.log(parameter); // Output = foo

const argument = "foo";


There are two kinds of parameters:

input parameters

the most common kind; they pass values into functions. Depending on the programming language, input parameters can be passed in several ways (e.g., call-by-value, call-by-address, call-by-reference).

output/return parameters

primarily return multiple values from a function, but are not recommended since they cause confusion

Parameters versus arguments

Note the difference between parameters and arguments:

  • Function parameters are the names listed in the function's definition.
  • Function arguments are the real values passed to the function.
  • Parameters are initialized to the values of the arguments supplied.

See also