JavaScript - Differences In Syntax?

Greeting Everyone,

Can anyone breakdown the differences between programming languages in VERY VERY BASIC plain English? (i.e. HTML use for website format, CSS used for the graphics on the webpage)

Here's what I have questions about:

1. Differences between the most commonly used programming languages for software/web development (Javascript, Ruby on Rails, Phyton, etc.).

2. How do you determine which programming languages to use?

3. What factors are considered?

Thank in advance for the people that reply. =)

The following code results in the exact same output.
Is there an advantage to using i++ over ++i (or visa-versa) in the loop?

Code:

<script type="text/javascript">
var tarr1 = [];  for (var i=0; i<10; i++) { tarr1.push(i); }
var tarr2 = [];  for (var i=0; i<10; ++i) { tarr2.push(i); }
alert(tarr1.join(',')+'\n'+tarr2.join(','));
</script>

Similar question for the increment method in the following:
Code:

<script type="text/javascript">
var tarr1 = []; var i=0;  do { tarr1.push(i); i++; } while (i<10);
var tarr2 = []; var j=0;  do { tarr2.push(j); ++j; } while (j<10);
alert(tarr1.join(',')+'\n'+tarr2.join(','));
</script>

Hello,

As a novice, I'm not sure which one to use though. I'm trying to do a calculation with numbers in JavaScript using variables, particularly adding variables. Any guided understanding of this concept is welcome.
For example:
Code:

n = parseint(n) 
document.write(n += m)

A week or so ago Old Pedant and I discussed methods of converting string inputs to numbers. I speculated that *1 might be quicker. I have now run a test:-

Code:

<script type = "text/javascript">

var start = new Date().getTime();
for (var i =0; i <100000; i++) {
var a = "2";
a = a *1;
}
var end = new Date().getTime();
var diff1 = end - start;
alert (diff1); // 109

var start = new Date().getTime();
for (var i =0; i <100000; i++) {
var a = "2";
a = parseInt(a);
}
var end = new Date().getTime();
var diff2 = end - start;
alert (diff2); // 140

var start = new Date().getTime();
for (var i =0; i <100000; i++) {
var a = "2";
a =Number(a);
}
var end = new Date().getTime();
var diff3 = end - start;
alert (diff3); // 140


var start = new Date().getTime();
for (var i =0; i <100000; i++) {
var a = "2";
a = +a;
}
var end = new Date().getTime();
var diff4 = end - start;
alert (diff4); // 109

</script>

The results vary slightly with each run, but the conclusion is that there is no real difference between the methods - except for a = a*1 and a = +a which consistently comes in lower than parseInt() or Number(). But the differences are too small to be significant.

I'm a PHP guy and haven't used jQuery much. I have a script I found in a book and I am trying to get working and am having trouble. It's a drop down list. I am using it in place of an HTML select box, so I want to pass the value selected from the list along with the form in a hidden field. My question is how do I extract the value out of the JS function and get it into the hidden field?

Code:

$(document).ready(function() {
  createDropDown();

  $(".dropdown dt a").click(function(event) {
    event.preventDefault();
    var dropID = $(this).closest("dl").attr("id");
    $("#" + dropID).find("ul").toggle();
  });

  $(document).bind('click', function(e) {
    var $clicked = $(e.target);
    if (! $clicked.parents().hasClass("dropdown"))
      $(".dropdown dd ul").hide();
  });


  $(".dropdown dd ul a").click(function() {
    var dl = $(this).closest("dl");
    var dropID = dl.attr("id");
    var text = $(this).html();
    var source = dl.prev();
    $("#" + dropID + " dt a").html(text);
    $("#" + dropID + " dd ul").hide();
    source.val($(this).find("span.value").html())
  });
});

function createDropDown() {
  var selects = $("select.dropdown_value");
  var idCounter = 1;
  selects.each(function() {
    var dropID = "dropdown_" + idCounter;
    var source = $(this);
    var selected = source.find("option[selected]");
    var options = $("option", source);
    source.after('<dl id="' + dropID + '" class="dropdown"></dl>');
    $("#" + dropID).append('<dt><a href="#">' + selected.text() + '<span class="value">' + selected.val() + '</span></a></dt>');
    $("#" + dropID).append('<dd><ul></ul></dd>');
    options.each(function() {
      $("#" + dropID + " dd ul").append('<li><a href="#">' + $(this).text() + '<span class="value">' + $(this).val() + '</span></a></li>');
    });
    idCounter++;
  });
}

I'm learning to program, and am having some issues with the syntax of my "if" statement. I've looked online but still can't get it to work. Here's the code:

Code:

function checks(){
	if(document.myform.checkbox.checked == true){
		window.open("http://www.espn.html", "mywindow");
	}
	else{
		document.write("hello world");
	}
}
//document.write("hello world");}

I know the function is being called properly because when I hit "submit" on the form the document.write("hello world"); statement prints on a new page. But for some reason when I call the function and that part is commented out, nothing happens. Any idea what I'm doing wrong? I tried looking online but can't figure anything out. Thanks in advance.

I just found this forum! I'm glad because I wanted to ask some javascript questions before.

There was a question at work before at why one would use the following:

if (a=='1') ...

or

if ('1'==a) ...

Is there any kind of advantage of using one of the other?

Thanks for any response!

Code:

<html>
<head>
	<style>
	.errorWrapper {padding:0; margin:0; list-style-type:none; position:relative;}
	.errorBox {padding:5px; position:absolute; left:100px; top:100px; background-color:#BADA55;
		border-radius:5px; -moz-border-radius:5px; -webkit-border-radius:5px;
		box-shadow:2px 2px 2px #808080; -moz-box-shadow:2px 2px 2px #808080; -webkit-box-shadow:2px 2px 2px #808080;}
	li.errorBox {display:none;}
	</style>

	<script type="text/javascript" src="test.js"></script>
</head>

<body>
	<a href="#" onClick="show('test')">test</a>
	<ul class="errorWrapper">
		<li id="test" class="errorBox">This should remain hidden until the link is clicked. Lorem ispum dolor sit amet. Placetne tibi? Mihi placet.</li>
	</ul>
</body>

<!-- Contents of test.js -->
<!-- function show(boxName) {alert(boxName); document.getElementByID(boxName).style.display="block";} -->

</html>

wtf is wrong with this? I'm brand spanking new to js, so I don't even know how to begin to troubleshoot this. As far as syntax goes I haven't seen any glaring errors, which leads me to believe I'm trying to do something illegal? The alert box shows up, and the boxName variable contains the correct contents (the ID of the element I want to show), so I dunno what the problem is...

Quick reproduction of the problem above.

Code:

out += (out ? rogueArray[14] : rogueArray[13]) + arrayItem + ((vanWilder[arrayItem] !== null) ? = + encodeURIComponent(vanWilder[arrayItem]) : rogueArray[13]);

There is supposedly a syntax error here on the line up until [arrayItem in Dreamweaver. Any help?

Hi all,
I have some card/images and would like to have the first one displayed.Which i can do.

Then when I mouse click on the card/image it goes to another image for say 2 secs, then with out clicking goes back to the orignal card. I have played with the syntax for ages and also looked on the net and cannot get it right.

This is what I have so far.
Code:

<html>
<head>
<script>
var back = new Image();
back.src = "back.gif";// preloads the image.

var ace = new Image();
ace.src = "0.gif"; //Preload the Image

var two = new Image();
two.src = "1.gif";// preloads the image.

var three = new Image();
three.src = "2.gif";// preloads the image.

var four = new Image();
four.src = "3.gif";// preloads the image.

var five = new Image();
five.src = "4.gif";// preloads the image.
</script>
</head>
<body>
<img name="img0">
<img name="img1"> // what is this for?

<script>

document.images['img0'].src = back.src;//displays image
/*How do I have one card diplayed then mouseclick on that one card and another card will display for 2 secs 
then the card will go back to original card.
*/
</script>

</body>
</html>

Any ideas ?
Thanks heaps
Shayne

i get this error when ever i try to process the form:

There was a SyntaxError: Unexpected token < error due to an parsererror condition.


Javacsipt/jquery:

$(document).ready(function(){

$("#slide").click(function(){
$("#inner-wrapper").slideToggle();
});

$('form #response').hide();
$('#submit').click(function(e){

e.preventDefault();

var valid = '';
var required = ' is required';
var name = $('form #name').val();
var email = $('form #email').val();
var fname = $('form #fname').val();
var femail = $('form #femail').val();
var message = $('form #message').val();
var honeypot = $('form #honeypot').val();
var humancheck = $('form #humancheck').val();

//Error checking


if (name == '' || name.length <=2) {
valid = '<p>Your name' + required + '</p>';
}

if (!email.match(/^[_a-z0-9-]+(\.[_a-z0-9-]+)*@[a-z0-9-]+(\.[a-z0-9-]+)*(\.[a-z]{2,3})$/)) {
valid += '<p>Your email' + required + '</p>';
}

if (fname == '' || fname.length <=2) {
valid += '<p>Your friend\'s name' + required + '</p>';
}

if (!femail.match(/^[_a-z0-9-]+(\.[_a-z0-9-]+)*@[a-z0-9-]+(\.[a-z0-9-]+)*(\.[a-z]{2,3})$/)) {
valid += '<p>Your friend\'s email' + required + '</p>';
}


if (message == '' || message.length <=5) {
valid += '<p>A message' + required + '</p>';
}

if (honeypot != 'http://') {
valid += '<p><center>Spambots are not allowed.</center></p>';
}

if (humancheck != '') {
valid += '<p><center>A human user' + required + '</center></p>';
}

if (valid != '') {
$('form #response').removeClass().addClass('error')
.html('<strong>Please correct the errors below.</strong>' + valid).fadeIn('2000');
}else {
$('form #response').removeClass().addClass('processing').html('<center>Working...</center>').fadeIn('2000');

var formData = $('form').serialize();
submitForm(formData);

}

});

});

function submitForm(formData) {
$.ajax({
type: 'POST',
url: 'emailfriend.php',
data: formData,
dataType: 'json',
cache: false,
timeout: 7000,
success: function(data) {
$('form #response').removeClass().addClass((data.error === true) ? 'error' : 'success')
.html(data.msg).fadeIn('fast');

if ($('form #response').hasClass('success')) {
setTimeout("$('form #response').fadeOut('slow')", 5000);
}
},

error: function(XMLHttpRequest, textStatus, errorThrown) {
$('form #response').removeClass().addClass('error')
.html('<p>There was a <strong>' + errorThrown +
'</strong> error due to an <strong>' + textStatus +
'</strong> condition.</p>').fadeIn('fast');
},
complete: function(XMLHttpRequest, status) {
$('form')[0].reset();
}

});
};

php file

PHP Code:
<?php
  error_reporting(E_ALL ^ E_NOTICE);
  
  sleep(3);
  
  $name = stripslashes($_POST[name]);
  $email = stripslashes($_POST[email]);
  $fname = stripslashes($_POST[fname]);
  $femail = stripslashes($_POST[femail]);
  $message = stripslashes($_POST[message]);
  $honeypot = $_POST[honeypot];
  $humancheck = $_POST[humancheck];
  
  if ($honeypot == 'http://' && empty($humancheck)) {
  
      $error_msg = '';
      $reg_exp = "/^[_a-z0-9-]+(\.[_a-z0-9-]+)*@[a-z0-9-]+(\.[a-z0-9-]+)*(\.[a-z]{2,3})$/";
      
      if (!preg_match($reg_exp, $email)) {
         $error_msg .= "<p>A valid email is required</p>"; 
      }
      
        if (!preg_match($reg_exp, $femail)) {
         $error_msg .= "<p>A valid email is required</p>"; 
      }
      
      if (empty($name)) {
         $error_msg .= "<p/>Please provide your name</p>";
      }
      
      if (empty($fname)) {
         $error_msg .= "<p/>Please provide your name</p>";
      }
      
      if (empty($message)) {
          $error_msg .= "<p>A message is required.</p>";
      }
      
      if (!empty($error_msg)) {
         $return['error'] = true;
         $return['msg'] = "<h3>Oops! Looks like you missed a few fields.</h3>".$error_msg;
         echo json_encode($return);
         exit();
         
      }else {
        $return['error'] = false;
      
        $ref=@$HTTP_REFERER; 
        /////Message at the top of the page showing the url////
        $header_message = "Hi $fname \n Your friend $name requested you to visit this page at \n $ref \n";
        /// Body message prepared with the message entered by the user ////
        $body_message =$header_message."\n".$message."\n";
        // IP address of visitor is added to message, you can remove it if not required.//
        $body_message .="\n Sent from http://www.separatethescams.com";
        //// Mail posting part starts here /////////

        $headers="";
        //$headers = "Content-Type: text/html; charset=iso-8859-1\n".$headers; 
         // Un comment the above line to send mail in html format
        $headers4=$email;         // Change this to change from address
        $headers.="Reply-to: $headers4\n";
        $headers .= "From: $headers4\n"; 
        $headers .= "Errors-to: $headers4\n"; 

        $subject="$name visit this site!";

        mail($femail,$subject,$body_message,$headers);
      
         $return['msg'] = " <b><p><center>Thanks for spreading the word! :) " . "<font color='red'>" .$name .  "</font>" . " </p>" . "</b>" . "</center>";
         echo json_encode($return);
      }
      
  }else {
      $return['error'] = true;
      $return['msg'] = "<h3><center>0ops there was a problem submitting the data. Please try again!</center></h3>";
      echo json_encode($return);
  }

?>


html file

<html>
<head>
<link rel="stylesheet" href="ajaxform/form.css" type="text/css" media="screen"/>
</head>
<body>

<div id="wrapper">
<h3 id="slide">Email This Page To a Friend</h3>
<hr></hr>
<div id="inner-wrapper">

<form id="my_form" action="ajaxform/emailfriend.php" method="post">

<div id="response"><!--This will hold error message and response from server. --></div>
<div class="inputs">
<p>
<label>Name&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp ;&nbsp;</label>
<input name="name" type="text" placeholder="Your Name" class="required" id="name" size="30" />
</p>
</div>

<div class="inputs">
<p>
<label>Email&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbs p;&nbsp;&nbsp;</label>
<input name="email" type="text" placeholder="Your Email" class="required" id="email" size="30" />
</p>
</div>

<div class="inputs">
<p>
<label>Friend's Name&nbsp;&nbsp;</label>
<input name="fname" type="text" placeholder="Friend's Name" class="required" id="fname" size="30" />
</p>
</div>

<div class="inputs">
<p>
<label>Friend's Email&nbsp;&nbsp;</label>
<input name="femail" type="text" placeholder="Friend's Email" class="required" id="femail" size="30" />
</p>
</div>

<div class="inputs">
<p>
<label id="msg">Message&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</label>
<textarea name="message" cols="24" rows="5"type="text" placeholder="Message To Friend" class="required" id="message"></textarea>
</p>
</div>

<div class="button">
<input name="submit" type="submit" id="submit" value="EMAIL PAGE" />
</div>

<div class="inputs">
<input type="hidden" name="honeypot" id="honeypot" value="http://" />
<input type="hidden" name="humancheck" id="humancheck" class="clear" value="" />
</div>

</form>
</div> <!-- inner-wrapper end -->
</div>

<script type="text/javascript" src=" https://ajax.googleapis.com/ajax/libs/jquery/1.7.2/jquery.min.js"></script>
<script type="text/javascript" src="ajaxform/ajax_submit.js"></script>
</body>
</html>

Can someone point where i'm going wrong? I want to evaluate the values of 'miles' to be >=0 and 'putime' to between 0 and 24 only.
Code:

<script type = "text/javascript">
	function TaxiFare() {
	// calculates taxi fare based upon miles travelled
	// and the hour of the day in military time (0-23).

	var baseFare = 2.50;
	var costPerMile = 2.00;
	var nightSurcharge = 0.50; // 8pm to 6am, every night

	var milesTravelled = Number(document.getElementById("miles").value);
	var pickupTime = Number(document.getElementById("putime").value);

	var cost = baseFare + (costPerMile * milesTravelled);

	// add the nightSurcharge to the cost if it is after
	// 10pm or before 6am
	if (pickupTime >= 22 || pickupTime < 6) {
	cost += nightSurcharge;
	}
	if((document.getElementById('miles').value>=0)&&(document.getElementById('putime').value>=0||<=24) {
	alert("Your taxi fare is $"  + cost.toFixed(2));
	}
	else{return 0;}
	}

	</script>

I have a webpage that has "classes" that are dynamically populated. if a class is empty, or not populated, can I use JavaScript to hide the "class"? If so How?
Sorry for such a noob question. Thanks in advance for any help

I keep getting myself into trouble because I tend to use my Java reference when coding Javascript, and of course Javascript doesn't support all Java functions.

I've just discovered that apparently Javascript doesn't support the trim() function. But curiously, if I code it as:
mystring.trim()
then Firefox will handle it without any errors. (I haven't actually checked to see if whitespace is removed from around the string.)
But when I code it like this:
trim(mystring)
then firefox gives an error.

I've also found a couple of situations where I've made syntax errors, and Firefox gives no error message. This makes debugging tricky, since the only resource I have available is Firefox's Error Console. Safari has no error reporting whatsoever, AFAIK. MSIE seems to find some errors that Firefox misses, but I don't have MSIE on my main computer, so it's a nuisance to use.

As a hobbyist, I have no budget to buy Javascript development tools. Is there something free available that does a better job of finding errors?

On this page
http://jimpix.co.uk/ecards/262-no-words.html

I get this Javascript error in IE6:

Code:

Line: 5
Character: 1
Code: 0
Error Message: Syntax error
URL: http://jimpix.co.uk/ecards/262-no-words.html

I'm using the DebugBar add in for IE (http://www.debugbar.com/)

The error message in DebugBar is this:
http://jimpix.co.uk/junk/error.png

And the view-source of the page is he
http://jimpix.co.uk/junk/source-code.png

I don't get the error in Firefox 3 or IE7.

I can't work out how to fix it.

Any advice would be much appreciated.

Thanks!