[JS] To Read: "The Essentials of Writing High Quality JavaScript"

Question

Received through The Code Project Daily News:
For all just-starting Javascript writers as well as for the seasoned ones -- and the ones that think they know a trick or two : an excerpt by Stoyan Stefanov in honor of his new O'Reilly title “JavaScript Patterns”.
A single page article, but it's a long page, and describes enough super-duper coding practice top tips to make your mouth water for the full deal.
http://net.tutsplus.com/tutorials/javascript-ajax/the-essentials-of-writing-high-quality-j avascript/

Answer 1

George,
It looks like this:
First Script:
(function() {
//snip
for (var j = 0; supportScripts.length > j; j++) {
     if (myTPS.timingInfo) {
          var supportStart = new Date();
     app.doScript(supportScripts[j]);
     if (myTPS.timingInfo) {
          var supportEnd = new Date();
          myTPS.log(supportScripts[j].name + " duration: " + (supportEnd - supportStart) + " ms.", interactive);
} // end for
Support Script:
(function() {
     // include the event services object and functions
     #include 'LC250III:ScriptSources:TPSevServe.jsx'
     // ++++++++++++++++ Main code function follows +++++++++++++++++++++++
     function performFunction(aDoc, interactive, eventId, myTPS) {
          // Here's where the actual code that does something useful goes
          // In here, I had a loop where I used j but forgot to declare it with var
          // Like this:
              for (j = 0, 5 > j, j++) {
                    // whatever
     } // end performFunction
     // ++++++++++++++++ Kick-off Code starts here +++++++++++++++++++++++++
     // If the job.id scriptArg is defined, we're running under Publish
     var interactive = !(app.scriptArgs.isDefined("job.id"));
     // make our working object
     var myTPS = new TPSevServ();
     // locate the "active" document
     if (app.scriptArgs.isDefined("job.activeDocument")) {
          var aDoc = app.documents.item(app.scriptArgs.get("job.activeDocument"));
     } else {
          var aDoc = myTPS.findLiveDoc();
          if (aDoc === null) {
               myTPS.log("Couldn't locate active document.", interactive);
               return;
     var eventId = app.scriptArgs.get("job.eventId");
     try {
          performFunction(aDoc, interactive, eventId, myTPS);
     } catch(e) {
          myTPS.log("Error " + e.number + ": " + e.message + " at line: " + e.line, interactive);
It turned out that by failing to declare that deeply internal loop variable as a local (I think it was even deeper than I'm showing here in that it was inside a called function), I was accidentally using the same j as in the calling script. As a result, when the calling script tried to post the duration to the log, it got an error because the value of j was wrong for picking up the supportScript's name. The error was a cryptic "[21]".
At least next time I'll know what it means.
But it has shaken my confidence in the value of anonymous functions. I guess the point is that names inside an anonymous function don't leak upwards into the global space, but they can flow downwards.
Dave