How to test if a parameter is provided to a function?

Question

I was wondering, can you create a function with an optional parameter.

Example:

function parameterTest(test)
{
   if exists(test)
   {
     alert(\'t         


        

Answer 1

best way to check: if the param is not undefined

function parameterTest(param) {
    if (param !== undefined)
    ...

the param could be also a variable or a function name