Unapparent Parent in Knockout Binding Context

When working with KnockoutJS, the with binding allows you to change the current binding context. So if you have a nested data structure, instead of having to binding to properties such as subViewModel.property1 and subViewModel.property2, you can put them inside a with binding and then refer to them directly as property1 and property2, respectively.

This is quite useful in keeping your views from getting too cluttered when your viewmodel structure gets large. However, if you jump down more than one level in a single the with binding, it’s not immediately apparent what the $parent context will refer to.

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Clean Markup with Chrome Extension I18n

Having written both an IE extension and a Chrome extension, I must say that writing the Chrome extension was a far, far better experience. Let’s just say that I really don’t want to ever write an IE extension again.

For the IE extension, you have conflicting forum posts and MSDN articles from years ago that only partially apply to the current version of IE, and there isn’t any real documentation or developer’s guide to speak of. You can write the IE extension in C#, but there is no guidance on how to do so, and the prevailing advice is to write the extension in C++.

Chrome, however, provides a great developer’s guide, tutorials, and a wide collection of sample extensions. The Chrome extension is written completely in Javascript, CSS, and HTML, languages which web developers are already familiar with.

Now that I’ve finished my rant, let’s leave IE behind and focus on Chrome.

Today, we’ll be looking at adding internationalization (i18n) support to a Chrome Extension. We’ll also look at a pattern that uses the data-* attribute in HTML5 to provide clean markup that gets internationalized.

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Knockout binding for onbeforeunload

While continuing on my knockoutjs adventure, we recently had a need to prompt the user when they were leaving the page. A common use case for this is when the user is editing something and navigates away from the page before saving any changes. The navigation can be done by using the back button, a link on the page, or closing the browser or tab. Javascript provides a helpful event, the onbeforeunload event.

The typical pattern for using this event is as follows:

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window.onbeforeunload = confirmExit;
function confirmExit()
{

return "You have not saved your work."
}

You set onbeforeunload to a function that returns a string. The string will show up in a dialog box like this when navigating away:

This has been around for a while. But I wanted to be able to do this in a way that used the MVVM pattern in Knockout. I wanted to have this controlled by data binding between my markup and viewmodel.

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Cookies and IFrames Don't Mix

I’m not a fan of IFrames. Let’s just get that out on the table to start with. Every time I use one, it’s against my will and I always feel like it’s a kludge. There - I said it.

Why am I upset with IFrames today? I was trying to set some cookies in a IFrame, where the IFrame was loaded from a different domain from the main page, and the cookies refused to set. I was using the jQuery Cookie plugin, and my code looked like this:

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$.cookie('myCookie', 'Chocolate Chip');
alert($.cookie('myCookie');

And this is what I saw:

I was expecting to have ‘Chocolate Chip’ be shown in the alert. No such luck - my cookie was eaten by the browser.

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