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JavaScript - Trouble Checking Whether Id Exists Using A While Loop
Hi! I'm new to this forum and almost completely new to programming of any kind, so this may be a very easy, obvious fix; I'm just not sure. Below is a very simple script I wrote partially based on random example scripts. I think an error is generated when the while loop is first executed, because any code I place after the loop is not executed. My guess is that when null is returned, it crashes and stops executing the code. Is that the problem? If so, do you have any ideas for how I could fix it?
Thanks in advance for your help! HTML: Code: <a href="javascript:expand(document.getElementById('exp1'))">SeeText</a>
<div id="exp1" style="display:none">
<p>SomeText</p>
</div>
<a href="javascript:expand(document.getElementById('exp2'))">SeeText</a>
<div id="exp2" style="display:none">
<p>SomeText</p>
</div>
Javascript: Code: function expand(param)
{
i=0;
id="exp1";
if (param.style.display=="none")
{
while (getElementByID(id)) //This seems to be the trouble area.
{
document.getElementById(id).style.display="none";
i++;
id="exp"+String(i)
}
}
param.style.display=(param.style.display=="none")?"":"none";
}
Similar TutorialsHai Forum, May be this question is not in correct format, I want to know about how to check a particular file is exists or not ? using Javascript.One thing without using ActiveXObject because it is supports in IE only. Thanking You, Santosh Srinivas.G I'm trying to check to see if a dynamically created element exists BEFORE creating another element of the same exact type...but my if statement at the beginning is not working and another element is just created. Code: function writeElement(id) {
if(document.getElementsByTagName('transElement')[0]) {
var id = id;
killElement();
writeElement(id);
}
var id = id;
var transElement = document.createElement('transElement');
var solidElement = document.createElement('solidElement');
var closeElement = document.createElement('closeElement');
//transElement.id = "transElement";
transElement.setAttribute('id', 'transElement');
solidElement.setAttribute('id', 'solidElement');
closeElement.setAttribute('id', 'closeElement');
closeElement.setAttribute('onClick', 'killElement()');
closeElement.innerHTML = "Close";
var content = "inject_poem.php?id=" + id;
getdata(content, 'solidElement');
document.body.appendChild(transElement);
document.body.appendChild(solidElement);
document.body.appendChild(closeElement);
}
Does anyone know what is incorrect about my if statement? Hi, I know this is painfully obvious, but I can't get my head around it. Basically, these loops: Code: for (var p=0; p < routeInfo.length; p++) {
times = routeInfo[p].getElementsByTagName("time");
dirs = routeInfo[p].getElementsByTagName("dirs");
dist = routeInfo[p].getElementsByTagName("dist");
for (q=0;q<dirs.length;q++) {
count++;
time = GXml.value(routeInfo[p].getElementsByTagName("time")[q]);
dir = GXml.value(routeInfo[p].getElementsByTagName("dirs")[q]);
dist = GXml.value(routeInfo[p].getElementsByTagName("dist")[q]);
if (time.length>1) {
way+='<div class="dir">'+count+'. '+dir+'</div>'+'<div class="results"><div class="time">'+time+'</div><div class="dist">'+dist+'</div><br><br>';
}
else way+='<div class="dir">'+count+'. '+dir+'</div><br>';
}
}
outputs lines of text, with two <br> between them. What I want is for if it's the last loop for that only to be one <br> so I'm thinking something like this: Code: if (last loop) {end =<br>}
else end=<br><br>
...
way+='<div class="dir">'+count+'. '+dir+'</div>'+'<div class="results"><div class="time">'+time+'</div><div class="dist">'+dist+'</div>'+end;
but I can't figure out what that "last loop" code should be. Any ideas? Hi This part of the script should ask the user which type of shape they'd like to calculate the area of, then convert whatever they enter to uppercase so that the test condition can be eventually falsified when the user enters 'c, C, s, S, r or R'. I've consulted the w3 school, and as far as I can tell I'm formatting it correctly. I think the problem may be in the syntax of the test condition. Code: while (shapeType != 'C' || shapeType != 'S' || shapeType != 'R')
{
shapeType = prompt("Which type of Shape would you like to find the area of?" + '\n' + "For a circle, enter C" + '\n' + "For a square, enter S" + '\n' + " For a rectangle, enter R");
shapeType = shapeType.toUpperCase();
}
However, firebug reports that 'shapeType is null'. How can this be? I've declared shapeType in the head as a global variable. Any ideas? Jenny All I am trying to pull the data from an array and place it in a table. If I assign index 0 it works as desired. I then placed it inside a foor loop and changed the index to a variable and I get "undefined". Here is the code snipet: document.write("<table width='500'>"); document.write("<tr><td width='75%'>Product:</td><td width='25%' align='center'>Cost</td></tr>"); for (i=0; i<(itemPrice.length); i++); { document.write("<tr><td>" + itemName[i] + "</td><td align='right'>" + itemPrice[i] + "</td></tr>"); totalcost = totalcost + itemPrice[i]; } document.write("<tr><td>The total is:</td><td align='right'>" +"$ "+totalcost+ "</td></tr>"); document.write("</table>"); compared to some of the samples I have seen I apologize if this is too elementary. rneaul I'm just a beginner with JS and having trouble with the code for my array and FOR loop. I'd like the names of these animals to be listed on separate lines. Am I way off here? I wasn't sure if the for statement had to be within a function. I've spent hours trying to figure this out and appreciate any help. <script type="text/javascript"> var animal = new Array(4); animal[0] = "dog"; animal[1] = "cat"; animal[2] = "bird"; animal[3] = "rabbit"; var counter = 0; function writeAnimal () { for (var counter = 0; counter== 4; counter++) { document.write(animal[0]); document.write("<br />"); } } </script> This is the loop I'm trying to use to check for bullets hitting rocks. the function worked if I used actual numbers instead of the j variable, but I wanted to loop through all the rocks. Can anyone see why the inner function loses the j index and says asteroids[j] is undefined? the hit test is removing the bullets! it's working! the asteroids[j] was used in the hit test! I'm getting testy. LOL Code:
for(z in player.bullets){
for(j in asteroids){
if( pnpoly( asteroids[j].points_x, asteroids[j].points_y, player.bullets[z].x - asteroids[j].x, player.bullets[z].y-asteroids[j].y)==true) {
player.bullets.shift();
asteroids[j].hits++;
for(i in asteroids[j].points_x){
asteroids[j].points_x[i]*=.5;
asteroids[j].points_y[i]*=.5;
}
};
}
Here's the whole script. This is the asteroids script somebody needed help with a few days ago. I just couldn't resist making this. I love asteroids so much it's hard to describe. That game was simply the most awesome thing ever at the time. (I'm a product of the eighties) Code:
<html>
<head>
<title></title>
<script type="text/javascript" src="excanvas.js"></script>
</head>
<body>
<script>
function pnpoly(xp, yp, x, y){var c=0;for(i in xp){ j=i++;if((((yp[i]<=y)&&(y<yp[j]))||((yp[j]<=y)&&(y<yp[i])))&&(x<(xp[j]-xp[i])*(y-yp[i])/(yp[j]-yp[i])+xp[i])){c =!c}} return c}
var canvas = null;
var c2d = null;
//...
window.onload = init;
function init() {
thrustFlame=false
asteroids = [{
x: 470,
y: 290,
angle: 1.71,
inertia: .5,
inertiaAngle: 1.2,
points_x: [-30, -27, 5, 15, 30, 15,-5],
points_y: [ -5, 15, 30, 27, -5, -25, -30],
hits:0
},
{
x: 270,
y: 290,
angle: 1.71,
inertia: .75,
inertiaAngle: 1.9,
points_x: [-30, -10, 0, 20, 40, 20, -10],
points_y: [0, -20, -50, -30, 0, 20, 20],
hits:0
}]
player = {
x: 50,
y: 50,
angle: 1.71,
inertia: 0,
inertiaAngle: 0,
bullets:[]
}
canvas = document.getElementById('canvas');
ctx = canvas.getContext('2d');
setInterval(step, 60);
}
function step() {
for (i in asteroids) {
asteroids[i].angle += i % 2 == 0 ? .05 : -.05
asteroids[i].x < 0 ? asteroids[i].x = canvas.width : asteroids[i].x %= canvas.width
asteroids[i].y < 0 ? asteroids[i].y = canvas.height : asteroids[i].y %= canvas.height
asteroids[i].x += Math.sin(asteroids[i].inertiaAngle) * asteroids[i].inertia;
asteroids[i].y += -Math.cos(asteroids[i].inertiaAngle) * asteroids[i].inertia
}
ctx.fillStyle = "rgb(0,0,0)"
ctx.fillRect(0, 0, canvas.width, canvas.height);
for (u = 0; u < asteroids.length; u++) {
ctx.save();
ctx.beginPath()
Asteroid_draw(asteroids[u]);
ctx.closePath();
ctx.strokeStyle = "#eeeeff";
ctx.stroke();
ctx.restore();
}
ctx.save();
ctx.beginPath()
Player_draw(player);
ctx.closePath()
ctx.strokeStyle = "#eeeeff";
ctx.stroke();
ctx.restore()
if(thrustFlame){
ctx.save();
ctx.beginPath()
Player_drawFlame(player);
ctx.closePath()
ctx.strokeStyle = "#ff0000";
ctx.stroke();
ctx.restore()
thrustFlame=false
}
player.x < 0 ? player.x = canvas.width : player.x %= canvas.width
player.y < 0 ? player.y = canvas.height : player.y %= canvas.height
if (player.inertia > .025) player.inertia -= .025
player.x += Math.sin(player.inertiaAngle) * player.inertia;
player.y += -Math.cos(player.inertiaAngle) * player.inertia
for(i in player.bullets){
player.bullets[i].timer++;
if(player.bullets[i].timer > player.bullets[i].range)player.bullets.shift()
player.bullets[i].x < 0 ? player.bullets[i].x = canvas.width : player.bullets[i].x %= canvas.width
player.bullets[i].y < 0 ? player.bullets[i].y = canvas.height : player.bullets[i].y %= canvas.height
player.bullets[i].x += Math.sin(player.bullets[i].inertiaAngle) * player.bullets[i].inertia;
player.bullets[i].y += -Math.cos(player.bullets[i].inertiaAngle) * player.bullets[i].inertia
ctx.save();
ctx.beginPath()
ctx.fillStyle="rgba(255,255,0,1)"
ctx.arc(player.bullets[i].x,player.bullets[i].y,1.5,0,3.14,true)
ctx.fill()
ctx.closePath()
ctx.restore();
}
for(z in player.bullets){
for(j in asteroids){
if( pnpoly( asteroids[j].points_x, asteroids[j].points_y, player.bullets[z].x - asteroids[j].x, player.bullets[z].y-asteroids[j].y)==true) {
player.bullets.shift();
asteroids[j].hits++;
for(i in asteroids[j].points_x){
asteroids[j].points_x[i]*=.5;
asteroids[j].points_y[i]*=.5;
}
};
}
}
}
function Asteroid_draw(obj) {
ctx.translate(obj.x, obj.y)
ctx.rotate(obj.angle);
ctx.moveTo(obj.points_x[0], obj.points_y[0]);
for (i = 0; i < obj.points_x.length - 1; i++) {
ctx.lineTo(obj.points_x[i], obj.points_y[i]);
}
ctx.lineTo(obj.points_x[0], obj.points_y[0])
}
function Player_draw(obj) {
ctx.translate(obj.x, obj.y);
ctx.rotate(obj.angle);
//Points {0,-12}{7,5}{-7,5}
ctx.moveTo(0, -12);
ctx.lineTo(7, 4);
ctx.lineTo(-7, 4);
ctx.moveTo(-7, 4)
ctx.lineTo(0, -12);
}
function Player_drawFlame(obj) {
ctx.translate(obj.x, obj.y);
ctx.rotate(obj.angle);
ctx.moveTo(-2, 2);
ctx.lineTo(0, 12);
ctx.lineTo(2, 2);
}
document.onkeydown = function (event) {
keyDown(event)
};
function keyDown(event) {event=!event?window.event:event
if (event.keyCode == 32) {
player.bullets.push({x:player.x,y:player.y,inertia:player.inertia+10,inertiaAngle:player.angle,timer:0,range:40})
}
if (event.keyCode == 37) {
player.angle -= .1
}
/*left*/
else if (event.keyCode == 39) {
player.angle += .1
}
/*right*/
else if (event.keyCode == 38) {
thrustFlame=true
var x1= Math.cos(player.inertiaAngle)* player.inertia;
var y1= Math.sin(player.inertiaAngle)* player.inertia;
var x2= Math.cos(player.angle)* .2;
var y2= Math.sin(player.angle)* .2;
var xR= x1 + x2;
var yR= y1 + y2;
var lengthR= Math.sqrt(xR*xR+yR*yR);
if (lengthR==0){angleR=0}
var angleR= Math.acos(xR/lengthR);
if (yR<0)angleR= 0-angleR;
player.inertia=lengthR
// player.inertiaAngle = (player.inertiaAngle*19 + player.angle) / 20
player.inertiaAngle =angleR
}
/* up*/
else if (event.keyCode == 40) {
player = {
x: 50,
y: 50,
angle: 1.71,
inertia: 0,
inertiaAngle: 0
}
}
/*down*/
}
</script>
<canvas id="canvas" width="600" height="600"></canvas>
</body>
</html>
I'm using a loop to get the attributes of a series of <a> tags in an xml. Here's the code: Code: function getAttributes(){
for(var i=0;i <= totalSteps;i++){
whichLink = xmlDoc.getElementsByTagName("xml")[0].getElementsByTagName("a")[i].attributes.getNamedItem("href").value.split("?");
alert(whichLink);
if(whichLink[1]=="correctLink"){
alert("correctLink detected");
myMessage += whichLink[0];
}
}
displayMessage();
}
When I run the function, I get a "Object required" error for the getElementsByTagName("a")[i] line, and displayMessage() won't fire. The weird thing is, the alert(whichLink); and alert("correctLink detected"); commands both work correctly, and when I replace the i variable with a digit, like 1 , everything works smoothly (save for the fact that it only returns one of the urls I'm looking for). So something odd is going on with my loop variable, but I'm at a loss as to what. Anyone have any ideas? Appreciated as always, ~gyz I have the following code: ... var numberoffiles = array(); for (i = 1; $i <= totalNumberOfFiles; i++) { numberoffiles[i] = i; } ... I get an error saying that numberoffiles is undeclared or something What am I doing wrong? Do I need to declare it a global variable or something?? ALSO, why can't I do this: numberoffiles[] = i; I've seen code snippets that assign to the end of an array like this (Or maybe my problem is the scope of the variable??) Thanks OM I am trying to create a simple auto-calculate function for a webpage. What should be happening: The 'onchange' command should pass the 'price' of the item to the function, the function should then cycle through all the dropdowns (or checkboxes or fields) and calculate the total. What is happening: It is only picking up the last checkbox. It seems that the 'for' loop only remembers the last item in the array. What am I doing wrong? How can I get the code to remember all the items? thanks, Code: <script language="JavaScript" type="text/javascript">
function calculateTotal(price)
{
var total = 0;
var cList = ['sel1','sel2','sel3'];
for (i=0;i<2;i++);
var select = GetE(cList[i]); total+= price * (select.options[select.selectedIndex].value);
GetE("totalShow").innerHTML = total.toFixed(2);
}
function GetE(id) {return document.getElementById(id); }
</script>
<html>
<head></head><body>
<form id="form1" name="form1" method="post" action="">
<select name="sel1" id="sel1" onchange="calculateTotal(100)">
<option value="0">0</option>
<option value="1">1</option>
<option value="2">2</option>
<option value="3">3</option>
</select><br><br>
<select name="sel2" id="sel2" onchange="calculateTotal(200)">
<option value="0">0</option>
<option value="1">1</option>
<option value="2">2</option>
<option value="3">3</option>
</select><br><br>
<select name="sel3" id="sel3" onchange="calculateTotal(300)">
<option value="0">0</option>
<option value="1">1</option>
<option value="2">2</option>
<option value="3">3</option>
</select><br><br>
</form>
<br>total <span id="totalShow">0.00</span>
</body></html>
Hello, Really need some help with this code i found online to check to see if a page exists. i am kind of new to Javascript and to have this working would really help me out! Here is the code : Code: <script language="javascript">
var url = "http://www.google.com";
checkUrl(url);
function checkUrl(url) {
var request = false;
if (window.XMLHttpRequest) {
request = new XMLHttpRequest;
} else if (window.ActiveXObject) {
request = new ActiveXObject("Microsoft.XMLHttp");
}
if (request) {
request.open('GET', url, true);
if (request.status == 200) { //FAILING ON THIS LINE ("Unspecified Error")
alert ("File does exist");
}
}
alert("File does not exist");
}</script>
It seems to be failing on the .status line and it returns an Unspecified Error in the debugger. I am using IE9 if that makes any difference. I have also tried amending the IF statement to include the readyState == 4, i dont get the error, but it doesn't work as planned. Really appreciate any help. SJG hi.. I want to have a list of words (in an array or whatever just to work) if the user put that word in a textfield (onblur or onchange) a message popup (alert) appears. (Must be popup alert) but I dont know to code it. HELP! ex.: Code: function badwords() {
var badwords = new Array();
badwords =["badwords1","badwords2","AndSo-On"];
if badwords if written in textfield
alert("Badwords not allowed");
else
nothing happen
just continue with next textfield
}
<input type="text" name="" onBlur=badwords()>
Anyone please help I'm using ccs3PIE with my site. What I want to do is check if a DOM element has a css property like border-radius and then add a class to it. The problem I'm having is that I don't know how to check for the css property. I've been searching for it for a couple of hours now and I can't find anything that seems to work. Any ideas? Hello, through a javascript injection im trying to find out if a cookie exists on my computer. Here's the code I inject: Code: javascript: if (document.cookie.indexOf('_idp_session') != -1) alert('cookie is here'); else alert('cookie is not here');
and when visiting the options of my browser, I can locate the cookie, and i can see its there. Nevertheless my script keeps telling me its not there.. what am i doing wrong? Hello, I am looking for a way to tell from javascript if a file exists (on the server). I don't mind doing this with a .php script, if I have to, but the javascript still needs to know if the file exists. I thought the following javascript code might work: Code: var file_exists = <?php echo file_exists("OpenTokSessionId.txt"); ?>;
but it didn't. PHP parsed the php code, but it didn't assign the result value to the Javascript variable like its supposed to (or at least, it didn't seem to). When I looked at the page source after I uploaded it to the server, that line of code now looked like this: Code: var file_exists = ; Note that my server is setup to pass files with an .html or .htm extension to the php engine. That is why this kind of stuff can be done. But for some reason, php doesn't seem to be able to output bool values. I tried the following .php script, which I loaded directly in my browser, but it didn't output anything: PHP Code: <?php function fileExists() { return file_exists("OpenTokSessionId.txt")) } echo fileExists(); ?> So I changed it to the following, and it outputted "File does not exist.", which is the expected result: PHP Code: <?php function fileExists() { if (file_exists("OpenTokSessionId.txt")) echo "File exists."; else echo "File does not exist."; } fileExists(); ?> I have a script that I had written for me that works in IE (I guess its a ActiveX?) but I display it in the HTML page as the below HTML. I want to be able to tell in Javascript if this object is available in IE Code: <object id="IEPrinterChecker" classid="CLSID:506974F1-EA53-40C6-940A-4A1D47D5934B" width="0" height="0"></object> Listed below you can tell I can check if the plugin is available in Firefox without having to specify in the html the object. How can I do this in IE? Code: <script language="JavaScript">
var plugin;
if ( window.ActiveXObject ) {
// IE
alert("How do I check for the plugin here?");
} else {
var type = "application/printer-checker-component;version=1.0.0.1"; // your mimeType
if (navigator && navigator.mimeTypes){
var mt = navigator.mimeTypes;
for (var i = 0; i < mt.length; i++){
if (mt[i].type == type) {
plugin = mt[i].enabledPlugin;
if (plugin) break;
}
}
}
}
if(plugin) {
// insert object and/or test the plugin with script
alert("plugin is available");
} else {
alert("plugin not available or disabled");
}
</script>
Can I do something like the below to see if a form exists in a document. Code: if(document.theForm){
alert('form exists');
} I am tasked with making a function that can accept many different items and return whether or not they exist. Currently I am struggling on seeing if an object that holds all the methods for a button exists. I thought I could pass in the string name of the object then do a $('buttonObject').length >0 in the 'Exists' method to see if it was created yet. However this will never return true, and I cannot pass in the object into my exists function without it being created yet (throws error). So something like Exists(buttonObject) won't work, I'll have to pass in the string name of it (Exists('buttonObject')) or something else (I'm new to JS). So how do I go about testing whether or not it exists if I cannot pass in buttonObject, without quotes? Greetings, If I have a form like so: Code: <form> <input type="text" /> </form> How can I check if the input exists using DOM 0? Code: while (document.forms[0].elements[0].exists){
...do something
}
I guess that I could assign a default value and check for something in "document.forms[0].elements[0].value" but that is not the approach I wish to take. I need to loop through all of the elements of a form until there are no more regardless of ID/name/value, am I thinking about this wrong? I'm not entirely sure this is possible. I hope it is, and it doesn't seem to far-fetched or impossible. With JS, how would one go about checking if a user has DivX Web Player installed? Usually people put in code within the embed, so if it the player doesn't load, it would have the message behind stating the fact. However I haven't seen this used at all with DivX, instead, you see pop-up boxes, whether installed or not, stating "Don't have DivX Web Player? Get it here for windows or mac" I find this extremely annoying, and would never want such informalities on my website. |
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