JavaScript通过prototype给对象定义属性用法实例

<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}var officeSpace = new movie("OfficeSpace");var narnia = new movie("Narnia","Andrew Adamson");movie.prototype.isComedy = false; //add a field to the movie's prototypedocument.write(narnia.toString());document.write("<br />Narnia a comedy? "+narnia.isComedy);officeSpace.isComedy = true; //override the default just for this objectdocument.write("<br />Office Space a comedy? "+officeSpace.isComedy);//--></script>