<script language="javascript">
function toggle(id) {
alert('call');
if (document.getElementById(id).style.display == "none") {
alert('now visible');
document.getElementById(id).style.display = "";
} else {
alert('now invisible');
document.getElementById(id).style.display = "none";
}
}
</script>
</head>
<body onload="toggle('image1');alert('test_body');toggle('image2')">
<script language="javascript">
alert('test_pre_function');
toggle('image1');
alert('test_after_function');
toggle('image2');
</script>
Looks like a lot of code but it's pretty simple so i think most of you won't have troubles with it. toggle() should toggle the display status of divs containing images.
When the user enters the site the divs should hide, when everything is loaded the divs should show up. (onload)
Strangely enough, the function in the body (not in the body tag) only work half, i get and alert 'test_pre_function' and i get an alert 'call' (out of the function), but that's it.
The code in the body tag runs just fine.
I find this weird because it's supposed to do exactly the same twice and one time it runs, another time not, so i guess i must have made some stupid mistake.
Script is executed as soon as it is parsed. If image1 and image2 haven't been parsed when the script is executed, document.getElementById("image1") will return null so .style.display will throw a "is null or not an object error". This explains why the two alerts work - execution stops at the first document.getElementById(id).style.display == "none" line.
Move the script to after the image elements in the document and it should work.
<script>
alert(document.getElementById("image1")); // -> null
</script>
<img id="image1" src="some/image.jpg" />
<script>
alert(document.getElementById("image1")); // -> object
</script>
Are you missing this?
alert('now visible');
document.getElementById(id).style.display = "block";
Try this http://jsfiddle.net/hUDb4/
var toggle = (function() {
// an object to keep state for elements
var state = {};
return function(id){
document.getElementById(id).style.display = (state[id] = !state[id]) ? "none" : "block";
};
})();
toggle("myid"); // none
toggle("myid"); // block
But the main issue here is as others has stated that the DOM isn't ready until the document is fully loaded.
you have used alert in the body onload. basically once the alert will get executed, then it asks you to click OK. meanwhile the last function may gets delayed focus.
see below
<script>
alert(document.getElementById("image1"));
<img id="image1" src="some/image.jpg" />
alert(document.getElementById("image1"));
</script>
Related
I have a iFrame on my page thats display style is none. I have a javascript function to set the source and then set the display to block. The problem is that the iframe shows up before the content of it is loaded and thus I get a flickering effect. It goes white first and then displays the content. So I need to set the source, and when done loading all content of its source, only set its display style.
CSS & Javascript
.ShowMe{display:block;}
function(url)
{
document.getElementById('myIFrame').src = url;
document.getElementById('myIFrame').className = ShowMe;
}
It's simple as that:
<iframe onload="this.style.opacity=1;" style="opacity:0;border:none;
I would suggest you try the following:
<script type="javascript">
var iframe = document.createElement("myIFrame");
iframe.src = url;
if (navigator.userAgent.indexOf("MSIE") > -1 && !window.opera){
iframe.onreadystatechange = function(){
if (iframe.readyState == "complete"){
//not sure if your code works but it is below for reference
document.getElementById('myIFrame').class = ShowMe;
//or this which will work
//document.getElementById("myIFrame").className = "ShowMe";
}
};
}
else
{
iframe.onload = function(){
//not sure if your code works but it is below for reference
document.getElementById('myIFrame').class = ShowMe;
//or this which will work
//document.getElementById("myIFrame").className = "ShowMe";
};
}
</script>
Based on the code found here.
You could do this within the iframe:
window.onload = function () {
window.frameElement.className = 'ShowMe'; // 'ShowMe' or what ever you have in ShowMe variable.
}
Since you've tagged your question with [jquery], I assume you have executed the code within $(document).ready(). It is fired when the DOM is ready, i.e. it uses native DOMContentLoaded event (if available). window.onload is fired, when all resources on the page are ready.
I'm writing some code that will get executed before the DOM loads, basically, using Modernizr to get scripts. Now my issue is that I want to show a loading animation if the DOM loads and the scripts are still loading.
Modernizr is executed in the head. If I put the code to use document.getElementById in the head also, error is thrown because the DOM hasn't loaded. Now I have no idea how to solve this.
Here is the code I have so far:
<head>
<script>
var FileManager = {
IsLoading = false;
LoadRequiredFiles: function (config) {
config = config || {};
this.OnLoading = config.onLoadingCallback;
this.OnComplete = config.onCompleteCallback;
this.IsLoading = true;
if (this.OnLoading) {
this.OnLoading();
}
var self = this;
Modernizr.load([{
load: '/jquery.min.js',
complete: function () {
if (self.OnComplete) {
self.OnComplete();
}
self.IsLoading = true;
}
},
]);
}
};
var globalLoadingId = 'globalLoader';
FileManager.LoadRequiredFiles({
onLoadingCallback: function () {
document.getElementById(globalLoadingId).style.display = 'block';
},
onCompleteCallback: function () {
document.getElementById(globalLoadingId).style.display = 'none';
}
});
</script>
I used to execute this code below the <body> tag, and it worked. Now I moved it into the <head>. So I used to pass 2 callbacks to it. Now I'd rather attach events to it and handle them in the body (assuming thats where the DOM is loaded).
What I'd like to do:
<head>
<script>
FileManager.LoadRequiredFiles();
</script>
</head>
<body>
<script>
//Bind the event, not sure if this is even possible in javascript.
FileManager.OnCompleted += fileManagerCompleted;
fileManagerCompleted()
{
document.getElementById(globalLoadingId).style.display = 'none';
}
if(FileManager.IsLoading)
{
document.getElementById(globalLoadingId).style.display = 'block';
}
</script>
</body>
The page is your canvas for display. You can't show anything before it loads. It sounds more like you want a very small page to load (quickly) where you could display your progress and then your code could dynamically load/display the rest of the page with ajax calls and javascript showing progress as it goes. That's the only way to get out in front of the rest of the page load that I know of.
The only entirely reliable way to run a script that manipulates the DOM is to use the body onload event. (window.onload is popular, but not quite 100% reliable.)
There are some browsers that implement a onDocumentReady event that can be kind-of-sort-of faked in IE, but I don't recommend its use.
Using getElementById will not, by itself, throw an error if used in the head. You might be causing an error because you aren't checking the returned value, which will be null if an element with the specified id wasn't found, e.g.
var el = document.getElementById('foo');
if (el) {
// do somethig with el
} else {
// el wasn't found
}
Your problem is how to display the image only if the scripts are still loading and the page is visible. The simple answer is don't use client-side script loading, do it at the server. :-)
If you want to persist with script loading, add a class to the loading image, say "hideOnLoad". Have a callback from the last script load that sets the rule to "display: none" (just create and add style sheet with that one rule using script).
Now you just include the loading image as the first element in the body with a class of "hideOnLoad", knowing that when scripts have finished loading they will hide the image regardless of whether it (or any other element with the same class) existed at the time or not.
I'm trying to write a simple javascript snippet which delays the image loading by a certain number of millisecs below.
<html>
<head>
<script type="text/javascript">
function SetTimer()
{
var Timer = setInterval("showImage()",3000);
}
function showImage()
{
document.getElementById('showImage').style.visibility = 'visible';
}
</script>
</head>
<body onLoad="SetTimer()" style="visibility:hidden">
<div id=showImage>
<img src="gwyneth_paltrow_2.jpg">
</div>
</body>
</html>
Am I approaching this incorrectly?
thanks in advance
This is basically an OK approach.
There are some bugs, namely:
document.getElementByID('showImage')style.visibility = 'hidden';
getElementByID should be getElementById
needs a dot after ('showImage')
You are setting the visibility to 'hidden' in order to show it. Instead, you should start out as hidden, and then make it appear instead of disappear.
document.getElementById('showImage').style.visibility = 'hidden';
Well, the code is backwards given the stated goal of delaying the appearance of the image. If I just use your code as a basis, then I would have the visibility of the image as hidden, using CSS, and then trigger the display to visible on the timer.
However, having said that... This doesn't delay the loading of the image, it merely delays the display of it. The other way to handle it is to use the timer to load an Image object in Javascript and then insert it into the DOM. This, then, will actually delay the loading of the image for 3 seconds. Something like this:
function showImage()
{
var myImage = new Image();
myImage.src = "gwyneth_paltrow_2.jpg";
document.getElementById("showImage").appendChild(myImage);
}
I'm doing that from memory, so syntax may not be entirely correct.
I have javascript that working fine in Firefox 3.x.x, but it does not work in IE*, Chrome, Safari. Simple alert work before calling function. Here is the code
function showDiv(div){
//alert(div);
document.getElementById(div).style.visibility='visible';
document.getElementById(div).style.height='auto';
document.getElementById(div).style.display='block';}
function hideDiv(div){
//alert(div);
document.getElementById(div).style.visibility='hidden';
document.getElementById(div).style.height='0px';
document.getElementById(div).style.display='none';
}
here is the html page code
<td align="center"><a onclick="showDiv('<?=$val['keyname']?>')" style="cursor:pointer;">Edit</a></td>
if I put alert() before showDiv('<?=$val['keyname']?>') then alert box is displayed but the function is not called in other browsers other than fire fox
Please tell me the solution for this.
The syntax looks okay to me.
Make sure there are not multiple elements with the same ID in the document and that your element IDs are valid.
There is nothing inherently wrong in the code you have posted. I suggest you post a reproduceable non-working example: the problem will be elsewhere in the page. Maybe the div ID string isn't unique (this is invalid HTML and will make behaviour unreliable); maybe there's some other script interfering, maybe you have event code firing this that's not written in a cross-browser way
However your attempts to hide an element in three different ways seem like overkill to me. Just a single display change would do it fine.
Another way to do it is to set className='hidden' or '', and use a CSS rule to map that class to display: none. The advantage of this is that you don't have to know whether the element in question is a <div> (that should revert to display: block), a <span> (that should revert to display: inline) or something else. (The table-related elements have particular problems.)
Maybe you could try that:
function showDiv(div) {
var obj = document.getElementById(div);
if (obj) {
obj.style.display = "block";
obj.style.height = "auto";
} else {
alert("DIV with id " + div + " not found. Can't show it.");
}
}
function hideDiv(div) {
var obj = document.getElementById(div);
if (obj) {
obj.style.display = "none";
} else {
alert("DIV with id " + div + " not found. Can't hide it.");
}
}
Do not call document.getElementById several times in the same function, use a variable to store the div element.
The if (obj) test will only execute the code if it has been found by document.getElementById(...).
So, I have this between my head tags
<script type="text/javascript">
hidden_links = document.getElementsByName("javascript_needed");
for (i = 0; i < hidden_links.length; i++) {
hidden_links[i].style.display = "visible";
}
</script>
And my divs are all similar to
<div name="javascript_needed" style="display: none;">stuff</div>
the overall goal here, is to have these divs hide when javascript is disabled, and re-enable them when javascript is enabled.... but for whatever reason, my code doesn't work. I ever tried it in the webkit console, and nothing errored =\
The JavaScript is executed before the divs are in the DOM. The standard way to do something after the DOM is ready is to use jQuery's $(document).ready(function () { });, but there are other ways as well.
The oldschool way is to use <body onload="myfunction()">.
Here's a newer way (edit: put display:none into CSS):
HTML:
<p class='javascript_needed'>hello</p>
CSS:
.javascript_needed {display:none;}
JavaScript:
$(document).ready(function () {
$('.javascript_needed').show();
});
Your JS should be setting the div's display to "block" ("visible" isn't a valid value for display).
Also, from the looks of things your elements aren't in the DOM at the time the code is fired (your code doesn't see them yet). Do any of the following:
Place your code anywhere in the document body below the divs
or, use an unobtrusive strategy to fire your function on window load, a la:
function addLoadEvent(func) {
var oldonload = window.onload;
if (typeof window.onload != 'function') {
window.onload = func;
} else {
window.onload = function() {
if (oldonload) {
oldonload();
}
func();
}
}
}
addLoadEvent(nameOfSomeFunctionToRunOnPageLoad);
or, Use a JS framework's "ready" functionality, a la jQuery's:
$(function () {
nameOfSomeFunctionToRunOnPageLoad();
});
"visible" is not a valid value for "display". You're after "inline" or "block".
"visible" and "hidden" are valid values for the "visibility" CSS property.
Difference between display and visible:
An element that is visible still takes up space on the page. The adjacent content is not rearranged when the element is toggled between visible and hidden.
An element that is display=none will not take up any space on the page. Other display values will cause the element to take up space. For example, display=block not only displays the element, but adds line breaks before and after it.
The disadvantage of showing elements on ready is that they will only flicker in after the page has finished loading. This usually looks odd.
Here's what I usually do. In a script in the <head> of the document (which runs before the body begins to render), do this:
document.documentElement.className = "JS";
Then, any CSS selectors that descend from .JS will only match if JavaScript is enabled. Let's say you give your links a class of javascriptNeeded (a class is more appropriate than a name here). Add this to your CSS:
.javascriptNeeded{
display: none;
}
.JS .javascriptNeeded{
display: inline;
}
…and the elements will be there from the start, but only if JavaScript is enabled.