var - Javascript

toylet

function shownumber(val) {
// XBM format
var Head = "#define count_width 8\n"+
"#define count_height 16\n"+
"static char count_bits[] = {";
var Count, dig, tag;

Digit = new Array();
Digit[0]=Head+"0xff,0xff,0xff,0xc3,0x99,0x99,0x99,0x99,"+
"0x99,0x99,0x99,0x99,0xc3,0xff,0xff,0xff};";
// ... sniped ....
for (Count = 0; Count < val.length; Count++) {
dig=val.substring(Count, Count+1);
tag="<IMG SRC='javascript:Digit["+dig+"]' "+
"HEIGHT=16 WIDTH=8 ALIGN='absmiddle'>";
document.write(tag);
}
}

When I run shownumber("0"), an XBM would be disaplayed. But if I changed
the declaration for the array to:

var Digit = new Array();

shownumber() would no longer work. Why? Everything is contained in the
function. Why can't I use local variable for the array?

--
.~. Might, Courage, Vision. In Linux We Trust.
/ v \ http://www.linux-sxs.org
/( _ )\ Linux 2.4.22-xfs
^ ^ 12:08am up 1 day 28 min load average: 1.00 1.00 1.00

Jul 20 '05 #1

Subscribe Post Reply

1334

toylet

> tag="<IMG SRC='javascript:Digit["+dig+"]' "+

"HEIGHT=16 WIDTH=8 ALIGN='absmiddle'>";
document.write(tag);
var Digit = new Array();
shownumber() would no longer work. Why? Everything is contained in the
function. Why can't I use local variable for the array?

I think I knew the answer. Something to do with order of execution.

What's the proper style for declaring global variable in Javascript?

--
.~. Might, Courage, Vision. In Linux We Trust.
/ v \ http://www.linux-sxs.org
/( _ )\ Linux 2.4.22-xfs
^ ^ 12:14am up 1 day 34 min load average: 1.01 1.01 1.00

Jul 20 '05 #2

Douglas Crockford

> I think I knew the answer. Something to do with order of execution.

What's the proper style for declaring global variable in Javascript?

Generally, it is best to avoid global variables. When you cannot avoid
them, they should be defined before they are used.

http://www.crockford.com/#javascript

Jul 20 '05 #3

toylet

Douglas Crockford wrote:

I think I knew the answer. Something to do with order of execution.

What's the proper style for declaring global variable in Javascript?

Generally, it is best to avoid global variables. When you cannot avoid
them, they should be defined before they are used.

http://www.crockford.com/#javascript

you meant something like this?

<html><head>
<script type="text/javascript">
$global_var1 = new Array();
$global_var2 = 1;
$global_var3 = "";

Function one() {}
function two() {}

// main
window.onload = one;
</script>
</head><body>
</body></html>

--
.~. Might, Courage, Vision. In Linux We Trust.
/ v \ http://www.linux-sxs.org
/( _ )\ Linux 2.4.22-xfs
^ ^ 12:52am up 1 day 1:12 load average: 0.99 0.97 0.97

Jul 20 '05 #4

Lasse Reichstein Nielsen

toylet <toylet_at_mail.hongkong.com> writes:

you meant something like this?
(Missing DOCTYPE declration, required by HTML) <html><head> (Missing title element, also required) <script type="text/javascript">
$global_var1 = new Array();

I would write

var $global_var1 = new Array();

Using the "var" declaration at the top level (not inside a function body)
declares a global variable.

/L
--
Lasse Reichstein Nielsen - lr*@hotpop.com
DHTML Death Colors: <URL:http://www.infimum.dk/HTML/rasterTriangleDOM.html>
'Faith without judgement merely degrades the spirit divine.'

Jul 20 '05 #5

Douglas Crockford

>>> What's the proper style for declaring global variable in Javascript?

Generally, it is best to avoid global variables. When you cannot avoid
them, they should be defined before they are used.
you meant something like this? <html><head>
<script type="text/javascript">
$global_var1 = new Array();
$global_var2 = 1;
$global_var3 = "";

Function one() {}
function two() {}

// main
window.onload = one;
</script>
</head><body>
</body></html>

Close. Leave off the type="text/javascript". That is a Microsoftism that
didn't make it into the standard.

I would write

var global_var1 = [];
var global_var2 = 1;
var global_var3 = "";

Use var to distinguish a new definition from using an existing
definition. Avoid using '$'. It was intended for use by program
generators. It looks ugly. Also, I prefer [] to new Array() .
Watch the capitalization on 'function'. JavaScript is case sensitive.
I would define function one this way:

window.onload = function one() {};

Finally, I recommend that you run your stuff through JSLint.

http://www.crockford.com/javascript/lint.html

Jul 20 '05 #6

toylet

> (Missing DOCTYPE declration, required by HTML)

(Missing title element, also required)

Not related to javascript, it seems that these 2 tags are not sondier
important by most browsers. At least, the page could still be rendered.
--
.~. Might, Courage, Vision. In Linux We Trust.
/ v \ http://www.linux-sxs.org
/( _ )\ Linux 2.4.22-xfs
^ ^ 1:28am up 1 day 1:48 load average: 1.00 1.00 1.00

Jul 20 '05 #7

toylet

> Close. Leave off the type="text/javascript". That is a Microsoftism that

didn't make it into the standard.
what should it be? `lanaguage="javascript"`? Thanks.
definition. Avoid using '$'. It was intended for use by program
Sorry, I mixed things up with php and perl.
Finally, I recommend that you run your stuff through JSLint.

http://www.crockford.com/javascript/lint.html

will try.
--
.~. Might, Courage, Vision. In Linux We Trust.
/ v \ http://www.linux-sxs.org
/( _ )\ Linux 2.4.22-xfs
^ ^ 1:36am up 1 day 1:56 load average: 0.99 0.94 0.95

Jul 20 '05 #8

Lasse Reichstein Nielsen

toylet <toylet_at_mail.hongkong.com> writes:

[about <script type="text/javascript">]

Close. Leave off the type="text/javascript". That is a Microsoftism
that didn't make it into the standard.

what should it be? `lanaguage="javascript"`? Thanks.

You should use 'type="text/javascript"'. I think Richard managed to
misread it somehow. It is not related to Microsoft at all, but comes
from the HTML specification.

The type attribute is required by HTML 4, and the content type
"text/javascript" is the suggested value to use for Javascript content
(even though it is not standardized as a MIME type).

<URL:http://www.w3.org/TR/html4/interact/scripts.html#h-18.2.1>

/L
--
Lasse Reichstein Nielsen - lr*@hotpop.com
DHTML Death Colors: <URL:http://www.infimum.dk/HTML/rasterTriangleDOM.html>
'Faith without judgement merely degrades the spirit divine.'

Jul 20 '05 #9

Lasse Reichstein Nielsen

Lasse Reichstein Nielsen <lr*@hotpop.com> writes:

I think Richard

Make that Douglas. So much for short term memeory (I remembered two
newsgroups later, though :)

/L
--
Lasse Reichstein Nielsen - lr*@hotpop.com
DHTML Death Colors: <URL:http://www.infimum.dk/HTML/rasterTriangleDOM.html>
'Faith without judgement merely degrades the spirit divine.'

Jul 20 '05 #10

Similar topics

PHP & Authorize.net w/o cURL?

by: William C. White | last post by:

Does anyone know of a way to use PHP /w Authorize.net AIM without using cURL? Our website is hosted on a shared drive and the webhost company doesn't installed additional software (such as cURL)...

PHP

Observations regarding redirection

by: Albert Ahtenberg | last post by:

Hello, I don't know if it is only me but I was sure that header("Location:url") redirects the browser instantly to URL, or at least stops the execution of the code. But appearantely it continues...

PHP

If - ElseIf - SQL Select... ASP YES.. PHP NO ???

by: James | last post by:

Hi, I have a form with 2 fields. 'A' 'B' The user completes one of the fields and the form is submitted. On the results page I want to run a query, but this will change subject to which...

PHP

Experience with PHP & Oracle 9.2.0/OCI8

by: Ollivier Robert | last post by:

Hello, I'm trying to link PHP with Oracle 9.2.0/OCI8 with gcc 3.2.3 on a Solaris9 system. The link succeeds but everytime I try to run php, I get a SEGV from inside the libcnltsh.so library. ...

PHP

select from drop list to fill table column with text -- HOW ?

by: Richard Galli | last post by:

I want viewers to compare state laws on a single subject. Imagine a three-column table with a drop-down box on the top. A viewer selects a state from the list, and that state's text fills the...

PHP

Back button

by: Albert Ahtenberg | last post by:

Hello, I have two questions. 1. When the user presses the back button and returns to a form he filled the form is reseted. How do I leave there the values he inserted? 2. When the...

PHP

~ Help - counter script ~

by: inderjit S Gabrie | last post by:

Hi all Here is the scenerio ...is it possibly to do this... i am getting valid course dates output on to a web which i have designed ....all is okay so far , look at the following web url ...

PHP

MYSQL, PHP and Bind variables in SQL

by: Jack | last post by:

Hi All, What is the PHP equivilent of Oracle bind variables in a SQL statement, e.g. select x from y where z=:parameter Which in asp/jsp would be followed by some statements to bind a value...

PHP

Image Resize does not work

by: Sandwick | last post by:

I am trying to change the size of a drawing so they are all 3x3. the script below is what i was trying to use to cut it in half ... I get errors. I can display the normal picture but not the...

PHP

Migrating Website to Cloud - Emmanuel Katto

by: emmanuelkatto | last post by:

Hi All, I am Emmanuel katto from Uganda. I want to ask what challenges you've faced while migrating a website to cloud. Please let me know. Thanks! Emmanuel

General

Navigating the Data Structures and Algorithms (DSA)

by: BarryA | last post by:

What are the essential steps and strategies outlined in the Data Structures and Algorithms (DSA) roadmap for aspiring data scientists? How can individuals effectively utilize this roadmap to progress...

Algorithms / Advanced Math

Looking to do Android software development, any suggestions? Is flutter better?

by: nemocccc | last post by:

hello, everyone, I want to develop a software for my android phone for daily needs, any suggestions?

General

What is ONU?

by: marktang | last post by:

ONU (Optical Network Unit) is one of the key components for providing high-speed Internet services. Its primary function is to act as an endpoint device located at the user's premises. However,...

General

Changing the language in Windows 10

by: Hystou | last post by:

Most computers default to English, but sometimes we require a different language, especially when relocating. Forgot to request a specific language before your computer shipped? No problem! You can...

Windows Server

Problem With Comparison Operator <=> in G++

by: Oralloy | last post by:

Hello folks, I am unable to find appropriate documentation on the type promotion of bit-fields when using the generalised comparison operator "<=>". The problem is that using the GNU compilers,...

C / C++

Maximizing Business Potential: The Nexus of Website Design and Digital Marketing

by: jinu1996 | last post by:

In today's digital age, having a compelling online presence is paramount for businesses aiming to thrive in a competitive landscape. At the heart of this digital strategy lies an intricately woven...

Online Marketing

Discussion: How does Zigbee compare with other wireless protocols in smart home applications?

by: tracyyun | last post by:

Dear forum friends, With the development of smart home technology, a variety of wireless communication protocols have appeared on the market, such as Zigbee, Z-Wave, Wi-Fi, Bluetooth, etc. Each...

General

AI Job Threat for Devs

by: agi2029 | last post by:

Let's talk about the concept of autonomous AI software engineers and no-code agents. These AIs are designed to manage the entire lifecycle of a software development project—planning, coding, testing,...

Career Advice