Parameter Passing

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Parameter Passing

Not every function accepts parameters.
Not all values have to be passed as parameters -- global variables?
Using only Global variables can get messy
Pass only values needed by function -- parameters

Simple Example:

function about_you(name, age, shoesize){
     document.write("<h1>All About You</h1>");
     document.write("<p><strong>Your Name is:
          </strong>" + name);
     document.write("<p><strong>You Are</strong>"
           + age + "Years Old");
     document.write("<p><strong>Your Shoe Size is:
           </strong>" + shoesize);
}

That might be called like this as the page is loaded:

<html>
<head>
  <script language="javascript">

   function about_you(name, age, shoesize){
      document.write("<h1>All About You</h1>");
      document.write("<p><strong>Your Name is:
                     </strong>" + name);
      document.write("<p><strong>You Are</strong>"
                   + age + "Years Old");
      document.write("<p><strong>Your Shoe Size is:
              </strong>" + shoesize);
  </script>
</head>
<body onLoad="about_you('David', 37, 9)">
</body>
</html>

or simply like this from within another function of more complex script:

function another_function() {
  ......
  about_you('David', 37, 9);
  ......
}

How are parameters passes into to functions in JavaScript?

This is not what you might expect?

parameters are passed as arrays.
Every function has two properties with information about the parameters.

function.arguments
: The array of parameters that have been passed.
function.arguments.length
: The number of parameters passed into the function.

Dave Marshall
9/28/2001