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Parameter

files/en-us/glossary/parameter/index.md

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Parameters are named variables declared as part of a {{Glossary("function")}}. They are used to reference the {{Glossary("argument", "arguments")}} passed into the function.

For example:

js
const argument1 = "Web";
const argument2 = "Development";
example(argument1, argument2); // passing two arguments

// This function takes two values
function example(parameter1, parameter2) {
  console.log(parameter1); // Output = "Web"
  console.log(parameter2); // Output = "Development"
}

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 {{Glossary("argument","arguments")}} are the real values passed to the function.
  • Parameters are initialized to the values of the arguments supplied.

See also