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Setcookie - Pages 366-367

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#1 oderza

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Posted 16 May 2012 - 7:58 PM

I had some trouble with the steps on pages 366-367 when setting cookies. What was happening ( I think ) is that the following code (step 7 & 8) was looking for the id of the target:

var target = e.target || e.srcElement;

//The timer code here didn't effect my results, but was sitting between the problematic code
var expire = new Date();
expire.setDate(expire.getDate() + 7);

COOKIE.setCookie('theme', target.id, expire);
setTheme(target.id);

However if a cookie was already set, and you use getCookie('theme') to retrieve it, your value is a string. So the fix I came up with was to use and IF and ELSE:

var expire = new Date();

expire.setDate(expire.getDate() + 7);

if (typeof e == ‘string’) {
COOKIE.setCookie(‘theme’, e, expire);
setTheme(e);
} else {
var target = e.target || e.srcElement;
COOKIE.setCookie(‘theme’, target.id, expire);
setTheme(target.id);
}

This got my page to work, meaning that I could switch between the Themes, close my browser, and then see the last Theme used. Otherwise, you could still alternate between the two Themes when the the window was open, but it would not be retrieved properly.

I wanted to know if there was a better way to work around this? Using (typeof e == 'string') worked out in this scenario, but as a rookie I'm not 100% confident in this fix.

Also, since nobody else has brought this up, I wanted to make sure I didn't miss or screw up somewhere along the way. Sometimes obvious mistakes are preventing my code from working in the first place.

Thanks!
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#2 Larry

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Posted 18 May 2012 - 7:51 AM

Yeah, I don't quite understand what you're doing here. e is going to be an event object. Why would it be equal to a string?
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#3 oderza

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Posted 18 May 2012 - 5:24 PM

I'm using the code from theme.html, theme.js and cookies.js. When you select a theme and then close the browser, you are expecting that the 'theme' will be stored and then loaded from a Cookie. Upon reopening the page, the cookie is retrieved in the onload function of the theme.js file.


window.onload = function() {
'use strict';

// Add click event handlers to each theme link:
document.getElementById('aTheme').onclick = setThemeCookie;
document.getElementById('bTheme').onclick = setThemeCookie;

// Get the cookie's value:
var theme = COOKIE.getCookie('theme');

The final line in the getCookie code provided in cookies.js is:
return cookies[i].split('=')[1];
This sends back a string. In this case either aTheme or bTheme.

The next lines in theme.js are:

// If there was a value, set the theme:
if (theme) {
setThemeCookie(theme);
}

}; // End of onload anonymous function.

I think this is happening: Theme is selected -> a cookie is stored -> the page is closed -> the page is opened again -> a cookie is retrieved (as a string). This string (bTheme or aTheme) is passed to setThemeCookie. The value passed to setThemeCookie(e) is checked by:

if (typeof e == 'undefined') e = window.event;

But because e is being passed along as a string, it is not undefined. Then you try to use e.target || e.srcElement on a string, which is where I thought maybe this is failing and why the background (theme) is not loading when I reopen the page.

That is why I modified the setThemeCookie to check for a string first (aTheme or bTheme), else use an event object, which would be every other time (when you are clicking on the links to change the theme).

If I DON'T modify the setThemeCookie function, like I show in my original post, then the background color is white upon reopening the page. I wanted to make sure that setCookie and getCookie were working properly, so I inserted a document.getElementById('whatever').innerHTML = theme to show me the theme variable prior to sending it through setThemeCookie. It does indeed show me either aTheme or bTheme as the value when I open the page, so I know that both setCookie and getCookie are working properly.

I hope that I'm not missing something super obvious here and that I'm understanding everything correctly. Thank you greatly for your help and your patience.
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#4 Larry

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Posted 18 May 2012 - 6:11 PM

Sorry for the confusion. It's a simple mistake on my part, and I can see why you were confused. On the window load, if a cookie exists, the setTheme() function should be called, not setThemeCookie(). That should make everything right for you. Please confirm and I'll get that added to the errata. Apologies again for the confusion!

Alternative, to have it call setThemeCookie(), and renew the cookie (as suggested in the comments in the book), you would have to either pass an object to the setThemeCookie() function or rewrite setThemeCookie() as you're trying to do.
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#5 oderza

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Posted 19 May 2012 - 5:20 PM

Yes, this did help. Replacing setThemeCookie with setTheme did solve the problem of loading the theme upon reopening the page.

However, like you said above, I still need to pass something along to the setThemeCookie to restart the cookie. I wasn't sure how proper my fix was when I changed setThemeCookie. As far as passing an object to setThemeCookie (leaving setThemeCookie the way it is), I'm not really sure what I could pass to it (besides the onclick from the link).

Thanks
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#6 oderza

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Posted 20 May 2012 - 12:02 PM

I've decided to take this route and stick with it, that way I can leave the setThemeCookie function alone:

In the onload function I'm using:


if(theme) {
setTheme(theme);
var expire = new Date();
expire.setDate(expire.getDate() + 7);
COOKIE.setCookie('theme', theme, expire);
};

I'm pretty sure I've completely exhausted this topic. Thanks again for all of your help Larry! I start the final chapter today :D
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#7 Larry

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Posted 21 May 2012 - 7:49 AM

Excellent. Thanks for sharing that. My apologies for the confusion again. That was a last minute "feature change" I made, and you know what happens when you make last minute changes...

Hope you enjoy the final chapter!
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