Ok, so clearly this doesn't work. I'm just starting out with this cookie business, and I'm fairly new to Javascript as well. This is just a practice site I'm making for fun. Here's what I have so far:
<!DOCTYPE html>
<html>
<head>
<link href='http://fonts.googleapis.com/css?family=Cutive+Mono' rel='stylesheet' type='text/css'>
<link rel="stylesheet" href="cookies.css"/>
</head>
<body>
<div id="weusecookies">
<h1>We Use Cookies</h1>
<input type="button" value="ok" onclick="ok();"/>
</div>
<script>
var cookiesDiv = document.getElementById("weusecookies");
document.cookie="hasVisited=false; expires=18 Dec 2027 12:00:00 UTC";
if (hasVisited=true) {
cookiesDiv.remove();
}
function ok() {
document.cookie="hasVisited=true";
cookiesDiv.remove();
}
</script>
</body>
</html>
The primary problem so far is that that initial if statement is triggered right off, and the div disappears the second the page is loaded. How would I fix that? And if I fixed that, would this actually work?
Something like this should generally not be done with JavaScript - ideally you should use a server-side language to determine if the "hasVisited" cookie has been set, and if not then (and only then) should it output the "we use cookies" code.
However, failing this, you could proceed in the opposite direction: have no banner shown (or set it to display:none), and have JavaScript show the element if the cookie is not set.
... I just noticed the actual problem. if(hasVisited=true). = is assignment, and besides you haven't defined the hasVisited variable. You need code to read the cookies.
Related
I am a complete beginner to javascript. I am also new to this website. I am asking for help to complete an assignment. I have been trying for more than 4 hours by looking at lecture material and online for a solution. It is causing me a lot of unnecessary stress. Before javascript we only used CSS and Html. I was given 6 javascript tasks to manipulate the html file (taskc.html) already given to me.
The tasks are as follows
Make a statement to change contents of h1 from "Welcome" to "Text"
2nd statement should make an new alert window when the page loads that delivers a message explaining what the page is about
3rd statement should change the title to "text"
4th statement should log the contents (innerHTML) of the first paragraph element in the console.
5th statement should hide the contents of the second paragraph when the page loads
6th statement should change the contents of the header to have a new colour of your choice
Here is that html.
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>Task C - The Document Object Mode</title>
</head>
<body>
<h1 id="header">Welcome</h1>
<p id="first">This site uses JavaScript</p>
<p id="second">Javascript is very useful</p>
</body>
</html>
Because the actual coding im meant to add is meant to be in the .js file I was given. so I figured I had to link the js file in the html file so I added
<script type="text/javascript" src="taskc.js"></script>
With that out of the way I went to the lecture notes and I thought I would simply need to modify some of the code given to me there like
document.getElementById('demo').innerHTML = 'Hello World!';
When I put this code in brackets I got the error (document is not defined)
I modified it to match the requirements for task 1
here it is
document.getElementById('header').innerHTML = 'text';
I was confused because I didn't know what this error meant and of course Errors and how to fix them are never explained so I had to lookup how to resolve the error.
I found that to fix it I have to declare it as a variable so I ended up doing this.
var document = 'taskc.html';
When I did this for document, alert and console all the errors went away, but when I did a live preview only statement 1 was working
If anyone could help me fix this I would really appreciate because I don't understand enough javascript to be able to complete this in a reasonable amount of time.
So first: Please use Javascript functions to keep your code tidy and clean.
Example:
HTML:
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>Task C - The Document Object Mode</title>
</head>
<body>
<h1 id="header">Welcome</h1>
<p id="first">This site uses JavaScript</p>
<p id="second">Javascript is very useful</p>
<script type="text/javascript" src="taskc.js">test();</script>
</body>
</html>
function test(){
alert("This is a test!");
}
Always implement scripts that are document referenced at the bottom of your html.
If you use JQuery you can use following code to check document is loaded:
$(document).ready(function(){
//foo bar
});
I am messing around with JavaScript experimenting to get a feel for it and have already hit a problem. Here is my html code:
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN""http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Insert title here</title>
<link rel="stylesheet" type="text/css" href="styles.css">
<script type="text/javascript" src="testing.js"></script>
</head>
<body onload="writeLine()">
</body>
</html>
Here is the JavaScript testing.js:
function writeLine()
{
document.write("Hello World!")
}
Here is the style sheet styles.css:
html, body {
background-color: red;
}
So a very simple example, but I may have chose an awkward example, using on-load in a body tag. So the code above loads and runs the function, but the style sheet does nothing, unless I remove the script tags in the head. I have tried putting the script tags everywhere else, but nothing works. I have researched on-line how to properly link to JavaScript files, and have no found no clear solution, can anyone point out my error?
I have used JavaScript before, but I want a clear understanding from the beginning before I use it any longer
You cannot use document.write after the document is closed (which it will be when onload fires) without destroying the existing document (including links to stylesheets).
Instead, use DOM manipulation, which is covered by chapters 8 and 9 of the W3C JavaScript Core Skills.
Your problem is with the document.write() called in a wrong moment*. This method prints given text at current place in the page as was intended to work while the page still loads. Because you are calling it when the whole page was loaded, the results are unexpected (undefined?)
Instead you should manipulate the dom tree directly:
function writeLine() {
var text = document.createTextNode("Hello World!");
document.body.appendChild(text);
}
Actually in Opera browser I see red background for few milliseconds and then it goes back to white. Try commenting out document.write() - the background is as expected. Moreover you should include <script> tag at the end of body, but this won't solve your problem.
* to be honest, there is no good moment for calling document.write(), avoid it
In your particular example it doesn't matter where the script tag is added as the document.write command executes after the content is rendered, overwriting the existing content.
If you add an alert before overwriting the content you can see your page is red before it gets overwritten with Hello World.
I'm writing text to a page using document.write for a Chrome extension, but the associated custom CSS isn't applied:
<!DOCTYPE html>
<html>
<head>
<title>TITLE GOES HERE</title>
<link rel="stylesheet" href="css/popup.css" type="text/css" />
</head>
<body>
<script type="text/javascript">
...
function showFolder(folder) {
console.debug('FOLDER: '+folder.title);
document.write('<p>'+folder.title+'<br></p>');
}
</script>
</body>
</html>
The CSS is simple, just for debugging:
p {
color: red;
}
I can get it to work if I put the stylesheet link inside the function showFolder, but that can't be the proper way to do it. I'm learning jscript/CSS on the fly, so the answer is probably something remedial. Is the problem in the jscript, the CSS or both?
Use innerHTML.
<div id="towrite"></div>
then you can write in it like this:
div=document.getElementById('towrite');
div.innerHTML = '<p>'+folder.title+'<br></p>';
If you run your document.write() before the page finishes loading (perhaps calling your showFolder call directly from a script on the page), then the text will be written into the document as you might expect.
However, if you call document.write after the page loads, as in an event handler, you will be writing an entirely new page. This is usually not what you want.
Instead, follow Zoltan's advice and set the innerHTML property of an empty div.
I'm not javascript expert... I mainly use jQuery.. but try this, kind of makes sense:
<!DOCTYPE html>
TITLE GOES HERE
<script type="text/javascript">
...
function showFolder(folder) {
console.debug('FOLDER: '+folder.title);
document.write('<p>'+folder.title+'<br></p>');
}
</script>
<link rel="stylesheet" href="css/popup.css" type="text/css" />
EDIT:
So the above didn't work, but I just thought about another solution. When are you actually calling the function? Try to put it in <body onLoad="functionnamehere()">
No idea if that works, but give it a try.
How to use jquery cookies in showing/hiding elements in a page ? I got the plugin from here
Tried some method but i am not successful. I used slideUp() and slideDown() functions to show/hide elements.
When a element is slided up a cookie should be set. when the page is refreshed, the element should be in slided up position
How to apply cookie when slided up and how to get the cookie when page is refreshed ?
I need help !
I think the following is what you're looking for. Let me know if I am mistaken. Good luck!
http://jsfiddle.net/8VCJY/8/
- EDIT -
Sorry! My cookies were getting set backwards. It does work now (new link). Again, all apologies.
- EDIT -
Actually, I don't even know if it does work. It looked like it did, but then reviewing my code, I can't see how that could be right. All in all, I'm pretty sure that the setting of the cookie at the appropriate time and whatnot will at least get you on the right path. I think my usage of the plugin is wrong, to be honest (I've never used it before), but I gave it what I could. I hope it was at least somewhat useful to you.
Would this do the trick?
<!DOCTYPE html>
<html> <!-- xmlns="http://www.w3.org/1999/xhtml" lang="en" -->
<head>
<style type="text/css">
#outer {height:500px;width:500px;background-color:black;position:relative;}
#slide-me {height:50px;width:50px;background-color:white;position:absolute;top:250px;left:5px;}
</style>
<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.4.2/jquery.min.js"></script>
<script type="text/javascript" src="jquery.cookie.js"></script>
</head>
<body>
<div id="outer">
<div id="slide-me"></div>
</div>
<button type="button" id="myBtn">Slide it!</button>
<script type="text/javascript">
$slideObj = $('#slide-me');
var topOffset = $.cookie('myCookie');
if(topOffset)
$slideObj.offset({top: topOffset - $slideObj.height(), left:$slideObj.offset().left});
$('#myBtn').click(function() {
$slideObj.slideUp();
$.cookie('myCookie', $slideObj.offset().top);
});
</script>
</body>
</html>
P.S I'm using the Cookie plugin.
So I was thinking a simple way to deal with javascript being disabled by the browser would be the following:
<head>
<title>JavaScript Test</title>
<noscript>
<meta http-equiv="Refresh"
content="1;url=nojs.html" />
</noscript>
</head>
And having the nojs.html have something like:
<p>Return to test after enabling javascrpt.</p>
At the crash page.
This isn't my preferred method, but it's nice and simple until something more graceful can be worked out for users without javascript.
However, it is not valid to put a <noscript> element in the head section. The preliminary tests worked anyway, of course, but I'm superstitious when it comes to my code being valid, plus I'd hate for this to actually fail a field test.
So is there a valid way to do this? Perhaps wrapping the noscript in another element, like an object tag? Or some even simpler way I'm not thinking of?
I am not sure why you need to redirect to another page instead of just showing a message. I use JS and a little CSS to handle these situations for me. Something like this:
<head>
....
<script type="text/javascript"> document.documentElement.className += " js"</script>
<link rel="stylesheet" type='text/css' href="css/layout.css" media="all" />
</head>
<body>
<div id="noscript">Please enable JavaScript, then refresh this page. JavaScript is required on this site</div>
<div id="wrapper">
...
</div>
</body>
Then in layout.css:
#wrapper { display: none } /* Hide if JS disabled */
.js #wrapper { display: block } /* Show if JS enabled */
.js #noscript { display: none } /* Hide if JS enabled */
By doing it this way, the class is applied to the html element before the page is rendered so you won't get a flicker as the non-JS content is swapped out for the JS content.
Doug's solution is pretty good, but it has a few drawbacks:
It is not valid to have a class attribute on the html element. Instead, use the body.
It requires that you know what display type to set the element to (i.e. ".js #wrapper { display: block }").
A simpler, more valid and flexible solution using the same approach could be:
<html>
<head>
<!-- put this in a separate stylesheet -->
<style type="text/css">
.jsOff .jsOnly{
display:none;
}
</style>
</head>
<body class="jsOff">
<script type="text/javascript">
document.body.className = document.body.className.replace('jsOff ','');
</script>
<noscript><p>Please enable JavaScript and then refresh the page.</p></noscript>
<p class="jsOnly">I am only shown if JS is enabled</p>
</body>
</html>
With this, it's valid html (no class attribute on the html element). It is simpler (less CSS). It's flexible. Just add the "jsOnly" class to any element that you want to only display when JS is enabled.
The <noscript> tag cannot be in the <head>, it must be in the <body>
The common practice is to show a message instead of redirecting, as there is no way to redirect only if javascript is disabled.
You could do it the other way around, have the first page be nojs.html, and on that page use javascript to redirect to the main content.
If you truly want a valid way to do it, make your main page the nojs.htm page and use JS to hide all content before it's shown to the user and immediately redirect to the real main page using javascript.
I like Doug's solution. However, if you need to redirect, I would remember that while there is a spec and a standard, the world of web browsers is a dirty, imperfect world. Whether or not something is allowed by the spec is not as important as whether or not it works in the set of browsers you care about.
Just look at the source code of any major site... Most of them won't validate I'd bet :)
What about:
noscript{
z-index:100;
position:absolute;
top:0;
left:0;
width:100%;
height:100%;
min-height:1024px; background:#FFF;
}
And:
<noscript>
<p>Please enable Javascript on your browser.</p></noscript>