I’ve been asking myself, what is the difference between this tag:

<script language="javascript">

and this tag:

<script type="text/javascript">

After doing some googling, I found this documentation.

The “language” specifies the scripting language of the contents of this element. Its value is an identifier for the language, but since these identifiers are not standard, this attribute has been deprecated in favor of type.

Therefore, you can say goodbye to <script language="">

JSON is a format for communication between the server-side (PHP, JSP, ASP, etc…) and the client-side (javascript). The magic of it is that the response from the server-side can be easily converted to an object via the use of the eval() function. eval() (can be “evil”) is a function that gives you the possibility to execute some code in javascript from a string. To use eval() is not a good idea.

How can you JSON from PHP?

If you are using PHP 5.2.x and above, you can simply use PHP built-in function, json_encode() and json_decode(). This is an example how it works:

$i = array(
array(“id” => 1, “name” => “sumardi”),
array(“id” => 2, “name” => “hassan”),
array(“id” => 3, “name” => “ruby”)
);

echo json_encode($i);

And it will echo :

[{"id":1,"name":"sumardi"},{"id":2,"name":"hassan"},{"id":3,"name":"ruby"}]

How to JSON on Client-Side?

Use the eval() function on the Server-Side JSON text response. And then you can call JSON like this:

for(var i = 0; i < json.length; i++)
{
console.info(json.id + ” ” + json.name);
}

I have been working with Javascript and AJAX quite a bit recently. I always used alert() to debug something. At least to know that the script was able to call the method or something.

saveBtn = dojo.widget.createWidget(“Button”, {caption: “Save Settings”}, dojo.byId(“saveBtn”));
alert(saveBtn.caption);

This is annoying & traditional way. I’m lazy to use Venkman. After doing some Googling about Firebug functionality, I found console.log(). Now, I can do same thing by using Firebug Console.

saveBtn = dojo.widget.createWidget(“Button”, {caption: “Save Settings”}, dojo.byId(“saveBtn”));
console.log(saveBtn.caption);

At least it’s not messing up my screen. w00f! It also has different logging levels:

• console.debug()
• console.info();
• console.warn();
• console.error();
• console.trace();

For more, Console API

Over the past few weeks, I have been working with Dojo Toolkit. Dojo is a powerful javascript toolkit. In javascript, the var keyword is used to declare (or create) variables, but it is not required. What’s the difference between these two statements:

a. var x =17;
b. x = 17;

Short answer. Statement (a) is to create variable as a local variable and statement (b) is to create variable in the global scope.

Long answer. A variable declared outside a function is a global variable and a variable declared by assignment inside a function is also a global variable. A variable declared with var inside a function
is a local variable, and is accessible only within that function.

For example, look at this code,

<script type="text/javascript">
x1 = 2;
var y1 = 2;

function setX2()
{
x2 = 3;
var y2 = 3;
}
</script>

Both x1 and y1 are global variable and are accessible everywhere in the global scope. But variable y2 is a local variable and x2 is global. Basically, to var or not to var is legal declaration. But it’s a good practice to use var because the variable is scoped to the correct execution context.