Objects have "prototypes" from which they may inherit fields and functions.

<script type="text/javascript">

function movieToString() {

return("title: "+this.title+" director: "+this.director);

}

function movie(title, director) {

this.title = title;

this.director = director || "unknown"; //if null assign to "unknown"

this.toString = movieToString; //assign function to this method pointer

}

movie.prototype.isComedy = false; //add a field to the movie's prototype

var officeSpace = new movie("OfficeSpace");

var narnia = new movie("Narni","Andrew Adamson");

document.write(narnia.toString());

document.write("

Narnia a comedy? "+narnia.isComedy);

officeSpace.isComedy = true; //override the default just for this object

document.write("

Office Space a comedy? "+officeSpace.isComedy);

</script>