Defining and Calling Functions

JavaScript Tutorials - Herong's Tutorial Examples

∟Defining and Calling Functions

This chapter provides a quick introduction of using user defined functions in JavaScript. Topics include defining new functions; calling existing functions; passing primitive and object parameters; returning values; using local variables.

Defining Your Own Functions

Defining Your Own Functions - Example

Calling Your Own Functions - Example

Passing Parameters by Value or by Reference

Function Parameters Are Passed as Local Copies

Function Parameters Are Passed as Local Copies - Example

Global and Local Variables - Scope Rules

Global Variables - Examples

Local Variables - Examples

Collision of Global and Local Variables - Examples

"return" Statement and Return Value

Takeaways:

The "function (...) {...}" statement allows you to define your own function.
When calling a function, primitive parameters are passed by values. And Object parameters are passed by references.
After calling a function, the resulting value is a copy of the returned primitive value, or a reference of the returned object.
Parameters can be named or unnamed.
Unnamed parameters can be accessed inside the function through the built-in array: arguments[].
Variables declared inside a function has local scope limited to the function body.