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JavaScript - Javascript Maths Theory
Hey guys,
I'm pretty new to javascript and would like some help with the maths, or rather, the way which the math is calculated. Ok, let's say you have 2 variables, north and south and then we run the program... north = 10; (north at this point is obviously 10) south = north + 5; (south at this point is north + 5 which is 15) north = 2*2 - north + south My question here is, is the north (the one in bold) equal to 10 or the new north, 4? Thanks, Similar TutorialsHi, Please bear with me as I have zero knowledge of programming, or even if this is the right way to do this. I use a website that has (i believe) Javascript on that uses some maths, and I am looking to convert this webpage into excel... I wonder if someone could give me a pointer to convert the attached code into the excel format, or even just to highlight where the maths is so i can continue myself! Code: script is too long, so ive attached as a zip I've cannibalised some code from the jQuery supersized plugin that scales images to full screen size while retaining aspect ratio. However, I seem to be getting it wrong, and my maths is... well, appalling. The problem is that while it's resizing correctly to fit the width OR the height, it's not fitting the width AND the height. That is: If I adjust the window height, the image scales to fit the height, but goes outside the window width. If I adjust the window width, the image scales to fit the width, but goes outside the window height. If I adjust both (dragging the window corner) it seems to favour fitting the width. I am currently using only landscape images. I don't know if that has a bearing. This may well just be a logic issue, but my brain is just turning to jelly when I look at my code below: Code: var image_ratio = options.image_dimensions.height / options.image_dimensions.width;
var browser_ratio = browser_height / browser_width;
if (browser_ratio > image_ratio){
var target_height = browser_height;
var target_width = Math.floor(browser_height / image_ratio);
} else {
var target_width = browser_width;
var target_height = Math.floor(browser_width * image_ratio);
}
The code above works out some new image dimensions and is called when the browser is resized. The options.image_dimensions.height and options.image_dimensions.width variables represent the original dimensions of the image, and browser_height and browser_width are calculated from the window size. How can I make it fit either landscape or portrait images to the smallest available dimension of the browser? Hello! I am trying to find a script that allows you to open multiple browser tabs and then close each of those tabs, either one by one or all at once. Does anyone know how to do this please? Thanks so much for your help. I want to have another go at Javascript. I have several books on the subject but I find that my eyesight is a major problem. Therefore I want to try an on-line solution, preferably free. I have Googled, but there are so many that I am almost dizzy with the choices. Perhaps someone could recommend one. Not too fussy visually. My knowledge is VERY basic. Frank Does anyone know how to make URL links that use Javascript still work when users have Javascript disabled on their browser? The only reason I'm using JS on a URL is because my link opens a PDF file, and I'm forcing it not to cache so users have the latest version. I tried the <script><noscript> tags, but I'm not sure if I'm using it correctly, as my URL completely disappears. Below is my HTML/Javascript code: <p class="download"> <script type="text/javascript">document.write("<span style=\"text-decoration: underline;\"><a href=\"javascript:void(0);\" onclick=\"window.open( 'http://www.webchild.com.au/mediakit/Direct_Media_Kit_Web.pdf?nocache='+ Math.floor( Math.random()*11 ) );\" >The Child Magazines Media Kit</a></span> (PDF 1 MB) ");</script> <noscript><span style="text-decoration: underline;"><a href="http://www.webchild.com.au/mediakit/Direct_Media_Kit_Web.pdf" >The Child Magazines Media Kit</a></span> (PDF 1 MB)</noscript> </p> Thanks for any help, Michael Hi Guys, I am new at JavaScript and start to do some tutorials.What I am trying to do here is prompting user to input a name and if the name was valid the page(document) will display with all objects like the button.But if user enter a wrong name then the button will be disabled! I create the following code but it did not work <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <title>New Web Project</title> <script language="JavaScript" type=""> function changeColor(){ document.bgColor = "Gray"; } </script> </head> <body> <script language="JavaScript" type="text/javascript"> var person = ""; person = prompt('What is Your Name:'); if (person == "Foo") { document.write("<h1 />Welcome " + person); document.bgColor = "Yellow"; } else { document.write("<h1 />Access Denied!!!!"); document.bgColor = "Red"; document.getElementById("gree").disabled = true; } </script> <div> <p/><input id="gree" type="button" value="Gray " onClick="changeColor();"> </div> </body> </html> as you can see I used the: document.getElementById("gree").disabled = true; but it did not work , could you please give an idea how I can solve this problem? Thanks Hi, I have the following code snippet: test.html ====== <script language="javascript" type="text/javascript"> var testVariable = "test"; </script> <script language="javascript" type="text/javascript" src="test.js"> </script> test.js ===== var testVariable = window.top.testVariable; In firefox, I'm able to access testvariable defined within test.html in test.js. But in chrome, test.js couldnot get the window.top.testVariable field defined in test.html. Can any one please let me know how i can make it work in chrome?. Am i missing something here?. I want to insert this js snippet Code: function addText(smiley) {
document.getElementById('message').value += " " + smiley + " ";
document.getElementById('message').focus();
return false;
}
to a loaded iframe with name&id chtifrm. I can access it & change embed something in its html via using something like: Code: $(parent.chtifrm.document.body).append('<div id=\"smly\" style=\"cursor:pointer;float:left;top:200px;display:none;position:absolute;\"><\/div>');
.... Code: parent.chtifrm.document.getElementById('chatbox_option_disco').style.display == 'none'
but how do I insert js in the head of loaded iframe? Hi Guys I am trying to modify the functionality of my page. I want to be able to activate this piece of code using another javascript function. This is the code I want to activate: Code: <script type="text/javascript"><!--
$('#button-cart').bind('click', function() {
$.ajax({
url: 'index.php?route=checkout/cart/update',
type: 'post',
data: $('.product-info input[type=\'text\'], .product-info input[type=\'hidden\'], .product-info input[type=\'radio\']:checked, .product-info input[type=\'checkbox\']:checked, .product-info select, .product-info textarea, .date_data input[type=\'text\']'),
dataType: 'json',
success: function(json) {
$('.success, .warning, .attention, information, .error').remove();
if (json['error']) {
if (json['error']['warning']) {
$('#notification').html('<div class="warning" style="display: none;">' + json['error']['warning'] + '<img src="catalog/view/theme/default/image/close.png" alt="" class="close" /></div>');
$('.warning').fadeIn('slow');
}
for (i in json['error']) {
$('#option-' + i).after('<span class="error">' + json['error'][i] + '</span>');
}
}
if (json['success']) {
$('#notification').html('<div class="success" style="display: none;">' + json['success'] + '<img src="catalog/view/theme/default/image/close.png" alt="" class="close" /></div>');
$('.success').fadeIn('slow');
$('#cart_total').html(json['total']);
$('html, body').animate({ scrollTop: 0 }, 'slow');
}
}
});
});
//--></script>
And this is how I want the format of the function to be: function testsession() { if there is a session called 'hiredate' { activate the script above } else { var el = document.getElementById("product_data"); } } I just dont know how to write this in javascript Could you help me if possible please Hey, I've got to make the values of some textboxes change the co-ordinates of my sprite on a canvas and havent a clue on how to do it, Here is my form with the two textboxes and submit button: <form> x: <input type="text" name="x" /><br /> y: <input type="text" name:"y" /><br /> <input type="submit" value="Submit"/><br /> </form> And i need it so that they change the values of these: //this shows where my sprite will start on the canvas var block_x; var block_y; searched the internet for hours and cant really find anything i understand or works. any help is much appreciated I got an index.php Code:
<html>
<form action="bacakomik.php" method='post'>
<select name="kodekomik">
<option value='../komik1/|23'>Judul Komik1</option>
<option value="../komik2/|20">Judul Komik2</option>
<option value="../komik3/|10">Juduk Komik3</option>
<option value="../komik4/|20">Judul Komik4</option>
</select>
<input type="submit" />
</form>
<?php
echo ('<select>');
echo ('<option value= "'.$i.'">'.'Page '.$i.'</option>');
echo ('</select>');
?>
</html>
As you can see, each of the option brings specific value "../komik1/|23" komik1 is a directory | is a delimiter 23 is the pages in one chapter and can be considered also as how many images are there on a specific directory This is my bacakomik.php Code: <?php
$dirkomik = $_POST['kodekomik'];
$exploded = explode("|", $dirkomik);
echo ($exploded[0]); //picture directory
echo ("<br>");
echo ($exploded[1]); //total page in the comic
$pagecount = (int)$exploded[1];
//Take last posted value, process it right away
echo ('<FORM name="guideform"> ');
echo ('<select name="guidelinks">');
$i=1;
do {
echo ('<option value= "'.$i.'">'.'Page '.$i.'</option>');
$i= $i+1;
}while($i <= $pagecount); //Printing option and select
echo ("</select>");
?>
<input type="button" name="go" value="Go!" onClick="document.getElementById('im').src=document.guideform.guidelinks.options[document.guideform.guidelinks.selectedIndex].value+'.png';"> </FORM>
<img src="img0.jpg" id="im">
With the current code on bacakomik.php, I only can change the img src of id "im" in the same directory only. What I want is that the Javascript could "add" the "$exploded[0]" variable so that the picture can be loaded from different directory. Anyone can do this? I believe that the fix should be somewhere on input tag inside OnClick, or do you know where? Anyway, I found this on the net http://p2p.wrox.com/php-faqs/11606-q...avascript.html Please help me to those who can... All -- I have a JavaScript config file called gameSetting.js which contains a bunch of variables which configures a particular game. I also have a shared JavaScript library which uses the variables in gameSetting.js, which I include like so: <script type="text/javascript" src="gameSetting.js" ></script> <script type="text/javascript" src="gameLibrary.js" ></script> In gameSetting.js I have: $(document).ready(function() { // call some functions / classes in gameLibrary.js } in Firefox, Safari, and Chrome, this works fine. However, in IE, when it's parsing gameSetting.js, it complains that the functions that live in gameLibrary.js aren't defined. When it gets to parsing gameLibrary.js, the variables in gameSetting.js are reported as not being defined. I've tried dynamically bootstrapping the gameLibrary file using this function in document.ready for dynamic load... $.getScript("gameLibrary.js"); However, the same problem still happens in IE, where when it parses the files individually it's not taking into context the file/variables that came before, so it's not an out of load order problem. My options a 1) collapsing all the functions in gameLibrary.js and variables in gameSetting.js into one file. However, this is not practical because this is dealing with literally hundreds of games, and having a gameLibrary.js in ONE location for ONE update is what makes most logical sense. 2) figure out a way to get this to work where variables in file1 are accessible to file2 in IE (as it seems they are in other browsers). jQuery seems to be able to have multiple plugins that all refer to the based jQuery-1.3.2.js, so I know there is a way to get this to work. Help appreciated. Nero I wrote a log function that took note of various function calls. Thinking that functions are first class objects, and objects have properties, I made the name of each logged function a property of that function, e.g., brightenInnerPara.name = "brightenInnerPara"; Every browser I tried (Firefox, MSIE, Opera, Chrome, Safari) accepted the assignment, no problem. In Firefox and MSIE, the result was what I wanted: brightenInnerPara.name == "brightenInnerPara" But in the others, the result was: brightenInnerPara.name == null Question 1. Which Javascript is correct here? I favor Firefox and MSIE, not merely because they were willing to give me what I wanted, but also because it makes no sense to accept an assignment statement without throwing an error and then give it a null semantics, like Chrome, Opera, and Safari did. I found a workaround, using assignments like this: brightenInnerPara.prototype.name = "brightenInnerPara"; To my surprise, that worked in every browser. But I don't know why. It seems that such assignments are enough to cause each function to have its own distinct prototype. Question 2. Just how inefficient is my workaround, and why does it work? I'm very very new to coding. I need to make a very basic javascript game for school. I'm trying to modify this ball bouncing game, but the ball doesn't collide with the paddle. Where have I gone wrong? <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <title>HoffHop!</title> <style> #playingArea{ position: absolute; top: 100; left: 100; border: 2px solid black; width: 500; height: 500; background-color: rgb(192,192,192); } #paddle{ position: absolute; top: 470; left: 228; width: 64; height: 16; } #ball{ position: absolute; top: 18; left: 200; width: 34; height: 34; } #score{ position: absolute; top: 486; left: 0; width: 500; height: 14; font-size: 10pt; color: white; background-color: rgb(32,128,64); } </style> <script language="JavaScript"> //get info, process data, update screen objects //instance vars var ball; var paddle; var score; //initial speeds var dx = 5; var dy = 5; var currentScore = 0; var timer; //set initial conditions for ball and paddle var paddleLeft = 228; var ballLeft = 300; var ballTop = 4; function init(){ //instantiate HTML object instance vars ball = document.getElementById('ball'); paddle = document.getElementById('paddle'); score = document.getElementById('score'); //register key listener with document object document.onkeydown = keyListener; //start the game loop start(); } function keyListener(e){ if(!e){ //for IE e = window.event; } if(e.keyCode==37 && paddleLeft > 0){ //keyCode 37 is left arrow paddleLeft -= 4; paddle.style.left = paddleLeft + 'px'; } if(e.keyCode==39 && paddleLeft < 436){ //keyCode 39 is right arrow paddleLeft += 4; paddle.style.left = paddleLeft + 'px'; } } function start(){ //game loop detectCollisions(); render(); difficulty(); //end conditions if(ballTop < 470){ //still in play - keep the loop going timer = setTimeout('start()',50); } else{ gameOver(); } } function detectCollisions(){ //just reflect the ball on a collision //a more robust engine could change trajectory of ball based //on where the ball hits the paddle if(collisionX()) dx = dx * -1; if(collisionY()) dy = dy * -1; } function collisionX(){ //check left and right boundaries if(ballLeft < 4 || ballLeft > 462) return true; return false; } function collisionY(){ //check if at top of playing area if(ballTop < 4) return true; //check to see if ball collided with paddle if(ballTop > 470){ if(ballLeft > paddleLeft && ballLeft < paddleLeft + 64) return true; } return false; } function render(){ moveBall(); updateScore(); } function moveBall(){ ballLeft += dx; ballTop += dy; ball.style.left = ballLeft; ball.style.top = ballTop; } function updateScore(){ currentScore += 5; score.innerHTML = 'Sco ' + currentScore; } function difficulty(){ //as the game progresses, increase magnitude of the vertical speed if(currentScore % 1000 == 0){ if(dy > 0) dy += 1; else dy -= 1; } } function gameOver(){ //end the game by clearing the timer, modifying the score label clearTimeout(timer); score.innerHTML += " Game Over"; score.style.backgroundColor = 'rgb(128,0,0)'; } </script> </head> <body onLoad="init()"> <h1>Bask-A-Bounce</h1> <div id="playingArea"> <div id="paddle"> <img src="paddle1.gif"> </div> <div id="ball"> <img src="ball.gif"> </div> <div id="score"> Sco 0 </div> </div> <embed name="Baywatch" src="Baywatch.mp3" loop="false" hidden="true" autostart="true"> </embed> </body> </html> PHP Code: var values = { value1: 6, other: { value2: values.value1 + 1 } } Why can that not work? Is there something like this.parent.value1? Hi everyone, can someone please help me to find a way to rewrite this code function evenorodd( form ) { var x = new Number( form.x.value ); if( isNaN( x ) || x == "" ) { alert( "Not a number or no value entered" ); return ""; } for( var i = 0; i <= x; i++ ) ( i % 2 == 0 ) ? alert( i + " is even!" ) : alert( i + " is odd!" ); } the purpose is to show an alert box with a odd or even number Thanks in advanced! I designed a simple mobile in html , i want to link it to strings such that.... example : there are numbers from 0 to 9 and when ever i click on a number and then click on another after all the click i made and at last when i click on the " dial" (for example purpose) it should prompt all the numbers in sequence where i click. example to make it clear for my purpose : 1 2 3 4 5 6 7 8 9 * 0 # Dial (button) I clicked on "4" then "6" then "9" and then i hit the "dial" button the it shold show an alert box displaying "469" . I think it isn't a big challenge for you javascript coders. Please post the whole javascript code for this function, also the id's defined to the html separetly by you I am just learning and up on queries , so want your help Thaks a ton |
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