JavaScript Functions

JavaScript Functions

Introduction

A function is a block of JavaScript code that is defined once but may be executed or invoked any number of times. Functions are used to encapsulate code that performs a specific task. Sometimes functions are defined for commonly required tasks to avoid the repetition entailed in typing the same statements over and over. More generally, they are used to keep code that performs a particular job in one place in order to enhance reusability and program clarity.

JavaScript functions are parameterized or non-parameterized. A parameterized function definition may include a list of identifiers, known as parameters that work as local variables for the body of the function. Function invocations provide values or arguments for the function’s parameters. Functions often use their argument values to compute a return value that becomes the value of the function invocation expression.

JavaScript supports two types functions. They are

•         Pre-defined or Library Functions

•         User-defined Functions