JavaScript Function Parameters

Function parameters in JavaScript allow you to pass values into a function so it can perform tasks using those values. Parameters are defined in the function signature, and values passed to them are called arguments.

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What Are Parameters?

Parameters are variables listed inside the parentheses in a function definition.

Here, name is the parameter.

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Passing Arguments to Functions

Arguments are actual values passed to a function when it is called.

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Multiple Parameters

You can define more than one parameter separated by commas.

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Default Parameters

Default parameters assign a fallback value when no argument is provided.

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Rest Parameters (...)

Use rest parameters to accept a variable number of arguments as an array.

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Arguments Object (Pre-ES6)

Prior to ES6, the arguments object was used to access all passed arguments.

Note: arguments is not available in arrow functions.

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Destructuring Parameters

You can destructure arrays or objects directly in the parameter list.

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Key Takeaways

• Parameters are declared in the function; arguments are values passed when calling it.
• Use default parameters to provide fallback values.
• Use rest parameters (...) to gather extra arguments into an array.
• Prefer rest parameters over the legacy arguments object.
• Destructuring helps simplify object or array arguments for cleaner code.