Starting the Script!

The execution of the script is started by calling up the choreographer function from the index.htm file. At call time, the function is passed an argument, the 'preload' string. This value is simply a word, just like any other one. Actually, this function plays a big role and handles many different aspects of our menu. It is made up of several groups of instructions, each group being implemented as a case of a switch statement. The processing of the appropriate case depends on the argument received by the function:

200: function choreographer() {
201:    var arg = choreographer.arguments;
202:
203:   switch(arg[0]) {
204:    case 'preLoad' :

       [...]

216:       break;
217:       
218:   case 'layerSetup' :

       [...]

234:       break;

Do not worry now about understanding which bit of the code does what. Just spot the switch on line 203. It detects the argument passed to the function and executes the corresponding code. Since the argument passed to the function here is the above-mentioned 'preload' string, the instructions on lines 204 to 216 are executed. The break keyword on line 216 terminates the execution of the switch, and of the function, too, since there is no other instruction following the switch.

Don't let these calls to the choreographer function, such as choreographer('preLoad') or choreographer('layerSetup'), worry you. Just search for the case group of instructions corresponding to the passed argument and see what happens.