I am ok with HTML but awfully new to JavaScript and I know very little at this point. My question is for this web site I’m building. I need to know the exact JavaScript code and placement of the code in an HTML document for this goal. I would like this site to automatically load a certain page (1-31) depending on what day of the month it is (1-31). I don’t need to worry about what month or year it is, just the date in the month. For instance when it is the eleventh day in the month, page11.html will automatically load when you click on to the site. I would like it to take the time(Date) from the client side not the server. This way no mater what time zone your in the right HTML page will pop up at midnight.

Most people can’t give the exact javascript code placement of the code in an HTML document because it would always be buggy. They can give hints and/or snippets of code but rarely a complete working piece. Sorry…

Secondly, relying on javascript to do all this work would be a mistake because if javascript is disabled, the site will not work. Most users have javascript enabled but you should always think about web-crawlers (google, yahoo!, etc) that will try to index your page but will hit an empty page.

It’s always hard to guess all the reasons why someone would want a different page everyday of the month and I don’t know more about the project than what is written above. Considering this, maybe there are just parts of the page that are changing everyday and you could load them on the server-side thus having a single page loading including other pages depending on the day. The problem is that you would have to ask the timezone of the user and keep it in a cookie.

Just remember, javascript should not be a requirement to navigate in a site.

Finally, if I would really want to load a complete new page in javascript, I would do the following.

This is the way I would do it, do you have any other suggestions?

Stuart Cooper recently sent me a mail about threading in javascript and I turn to you, javascripters, to find the a solution for his problem. I sent the code on RefactorMyCode for refactorisation and they will automatically show up in the comments of this post (the site is an idea of Marc-André Cournoyer who is a very active developer from Montreal). Don’t be afraid to think outside the box. The solution may be completly different from what is already written.

function startup(){

setInterval(“pinger(‘live’,0)”,10000);
setInterval(“pinger(‘standby’,1)”,10000);
setInterval(“pinger(‘dev’,2)”,10000);
setInterval(“pinger(‘test1′,3)”,10000);
setInterval(“pinger(‘test2′,4)”,10000);
setInterval(“pinger(‘test3′,5)”,10000);
setInterval(“pinger(‘test4′,6)”,10000);

}

function pinger(server,divit){

console=document.getElementById(‘ping_div’ + divit);
console.innerHTML=”;
sendRequest(“../php/ping_sys2.php?target=” + server);

}

[/snippet]

(each server has its own named div to return to)

What I am seeing when I run this is the final pinger response from the callback and nothing else. I since added debugging into my XMLHttpRequest code so that it split out the server response progress.

[snippet]

readyXML=xmlReq.readyState;

[/snippet]

[snippet]

if(readyXML == 3){

data=”Serving …”;

}

if(readyXML == 2){

data=”Sent …”;

}

if(readyXML == 1){

data=”Opening …”;

}

[/snippet]

What I have observed is that when running the setInterval commands as above, all except the final request are “jammed” on readyState = 1 and appropriately responds with “Sending …”

however,

when I do the following (which is messy)

[snippet]

function startup(){

setInterval(“pinger(‘live’,0)”,1000);
alert(“something”);
setInterval(“pinger(‘standby’,1)”,10000);
alert(“something”);
setInterval(“pinger(‘dev’,2)”,10000);
alert(“something”);
setInterval(“pinger(‘test1′,3)”,10000);
alert(“something”);
setInterval(“pinger(‘test2′,4)”,10000);
alert(“something”);
setInterval(“pinger(‘test3′,5)”,10000);
alert(“something”);
setInterval(“pinger(‘test4′,6)”,10000);

}

[/snippet]

Each response is absolutely spot on and will continue to generate pings correctly. So in this case the script alert interrupts are forcing the callback request to trigger, whereas without the alerts its only the last request that triggers a callback. I have also tried using artificial timeout loops instead of alerts (which generate the odd browser “script running slowly” message) but to no avail.

At the moment I am almost resigned to having to create individual events (like rollovers, though I would much prefer the ping initialisation to occur window.onLoad()) that trigger the setInterval() … which also seems to work fine.

I am hoping that you may have come across a way of forcing the XMLHttpRequest to respond without forcing alerts or confirms on the user, in the time since the last update to the article.

Effects

Camilou asked

Is it too hard to a poor mortal like me to achieve that fancy effects that some libraries like Prototype do offer? I mean, that drag-and-drop stuff looks pretty complicated to me. Or maybe I am just too noob.

Drag-and-drop is complicated but not that much. Thousands of people have done it before the libraries-era. But, I’d say that if you want to achieve something similar to prototype, you’ll probably work for months. Prototype is the most known javascript library and if you start today, there’s little chance you will get as far as them. Sorry. But if you have a very different and easier way of doing things, maybe you’ll succeed.

Creating a new library

Frank Stepanski asked

If I want to start creating my own JS libraries, how do I start?

If you have no better idea than re-implementing what already exists in other libraries, you’ll never know where to start. A new library should fill a hole that is not filled by anyone else. So, you’ll find where to start the day that you will want to do something and that you won’t find any library that does it.

TimmyOnTime

We are still working on TimmyOnTime. TimmyOnTime is a time-management that uses instant messaging so you don’t forget to track your time. There are still places available for the alpha period. Please, give us some feedback.

There seems (to me anyway) to be an overuse of the “new” syntax in libraries. If I create an Ajax object is there a functional benefit to using: “new Ajax.Request(options)” verses something like “sendAjaxRequest(options)” It seems to me that by using “new” causes more hassle because you need to be sure the objects are properly disposed of. So is there a performance or functional benefit to this technique?

I had a hard time understanding the question (and I was too ass hole to ask…) so I’ll rephrase it in another way : is there a benefit from using object-oriented techniques VS procedural in javascript?

Procedural in javascript

Though javascript was not a procedural language from the start, it has been overused as such in the beginning (and it’s still is). That may be because people didn’t bother learning javascript and they copy/pasted functions from sites that offers low-quality javascript snippet. All they did was “hacking” the poorly written code to suit their needs. This technique worked for a long time but with the use of ajax and DHTML, it’s nearly impossible to have clean code that is not buggy and dirty.

Object-oriented in javascript

The new statement necessary implies the use of objects in javascript. You can have basic information about object in How to create objects in object-oriented javascript and in with the articles tagged Object-oriented of this site.

The benefit of object-oriented

There is one major benefit about object-oriented that creates a lot of other benefits : the cleanliness of the code. The other benefits from that are : the code is easier to maintain, to modify, to read and to explain.

OO applied

I’ll apply it to an example. I want to alert the sound of cat by ajax.

In a procedural way, you’ll approximatively have

The problems? You have a global variable to keep track of the ajax request. Because it could be use by every other functions that need ajax, you can’t make more than one request at a time. Also, there are nothing that binds the two methods together apart their names that are look alike. Now, just think of the code when you have 5 or 6 different type of requests. Your code will look like garbage.

In a object-oriented way, you would all write this ugly code in a separated object. Your main call to see the sound of a cat could be something like

The code from above still exists somewhere but the complexity is now hidden behind the Cat class.

I began by asking some friends to ask Dan (me) a javascript question. Here they are… and you know what? You can read them for free!

PM asked Dan : Does javascript can become a sort of bisexual slave that makes my toasts every morning?
Answer : I’m afraid that the answer is no. Javascript doesn’t offer that kind of feature but maybe you could be interested in How to use JSON.

Emile asked Dan : If a kid wants to begin using javascript, does he need a 10 000$ computer or he can use a metal wire and a battery to create binary?
Answer : You know what? It’s up to you to decide which one suits you best. 10 000$ computer? Fine. Metal wire and battery? Fine too. Isn’t it a perfect world? By the way, maybe you could be interested in How to use JSON.

Now, it’s up to you to Ask Dan a javascript question by sending a mail to dan@javascriptkata.com.

Did I mention that sending an email is… free!