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Data breakpoints in JavaScript

2016 Jun 17, 5:44

The other day I had to debug a JavaScript UWA that was failing when trying to use an undefined property. In a previous OS build this code would run and the property was defined. I wanted something similar to windbg/cdb's ba command that lets me set a breakpoint on read or writes to a memory location so I could see what was creating the object in the previous OS build and what that code was doing now in the current OS build. I couldn't find such a breakpoint mechanism in Visual Studio or F12 so I wrote a little script to approximate JavaScript data breakpoints.

The script creates a stub object with a getter and setter. It actually performs the get or set but also calls debugger; to break in the debugger. In order to handle my case of needing to break when window.object1.object2 was created or accessed, I further had it recursively set up such stub objects for the matching property names.

Its not perfect because it is an enumerable property and shows up in hasOwnProperty and likely other places. But for your average code that checks for the existence of a property via if (object.property) it works well.

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Windows Store App WebView Cross Origin XMLHttpRequest Behavior

2016 Jun 2, 6:45

TL;DR: Web content in a JavaScript Windows Store app or WebView in a Windows Store app that has full access to WinRT also gets to use XHR unrestricted by cross origin checks.

By default web content in a WebView control in a Windows Store App has the same sort of limitations as that web content in a web browser. However, if you give the URI of that web content full access to WinRT, then the web content also gains the ability to use XMLHttpRequest unrestricted by cross origin checks. This means no CORS checks and no OPTIONS requests. This only works if the web content's URI matches a Rule in the ApplicationContentUriRules of your app's manifest and that Rule declares WindowsRuntimeAccess="all". If it declares WinRT access as 'None' or 'AllowForWebOnly' then XHR acts as it normally does.

In terms of security, if you've already given a page access to all of WinRT which includes the HttpRequest class and other networking classes that don't perform cross origin checks, then allowing XHR to skip CORS doesn't make things worse.

PermalinkCommentsjavascript uwa uwp web webview windows winrt xhr

Tweet from David_Risney

2016 Jan 17, 5:11
Guess where we were yesterday? #MonsterJam pic.twitter.com/a7AbM1eIlV
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Retweet of lukew

2016 Jan 6, 6:33
Web vs. native apps or why you want both (with data) http://www.lukew.com/ff/entry.asp?1954 … pic.twitter.com/wuEkpsyWo2
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Tweet from David_Risney

2015 Dec 14, 12:28
First thought was: How did a character encoding issue get that far? pic.twitter.com/TIxrbLcylO
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Retweet of kumailn

2015 Jul 18, 4:55
I had been trying to stay calm & approach it like any other job. And then I freaked out soon as I saw this. pic.twitter.com/reBKXIlXQ4
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Retweet of TheOnion

2015 Mar 11, 9:58
"We’ll be able to systematically deceive investors in the time it takes to press a button." http://onion.com/18fgr3J  pic.twitter.com/8E8QiIk5m6
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Retweet of dstorey

2015 Mar 11, 7:38
Whoops. Don't think that tells me when the bus is due. pic.twitter.com/4veVoB8Hlo
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Retweet of JustRogDigiTec

2015 Mar 1, 2:55
Saw something like this on someone's door. Found it funny. Only because it is painfully true. And I just saw one. pic.twitter.com/RmR6J1pF6r
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Parents Visited

2009 Aug 25, 12:34

My parents visited this past weekend, met Sarah's parents, saw our house, and met our bunny. On Friday we went to BluWater in Kirkland which was pretty busy and the service was slower and slightly worse than we usually find. Saturday my parents helped us with our yard quite a bit and for dinner we went to the Icon Grill with Sarah's parents. I had forgotten how much I enjoy the food at the Icon Grill - I had the very tasty meat loaf. Dinner went well and afterward we stopped at the Three Lions pub in Redmond. On all previous occasions I had tried to go in there the place was packed for a soccer game. This night however there was a man with a guitar, singing and it wasn't nearly as packed. I also found that near the bathrooms on the wall is what looks to be James Bond's jetpack.

On Sunday we went out to see Jeannie and Carl and see the renovations to Jeannie's place. We met up with them at the Fremont Market to which I hadn't been previously, and had a look around there before going back to Jeannie's to see the lovely work they'd done to her place. For dinner my parents took us out to the Melting Pot for my approaching birthday. It was fun having my parents up and I look forward to the next time they're here.

PermalinkCommentsfamily weekend

Visiting College Friends and Vice Versa

2008 Apr 27, 4:51

Jesse, Nicole and Pat in his carLast weekend after Saul and Ciera's wedding, I drove up to Pat, Grib, and Jesse's house to which I hadn't previously been. I got in late and they'd just finished a UFC party. The next day Grib had to travel for work but the rest of us met Scott and Nicole, Jesse's girlfriend at a place for breakfast. After that we went back to their place for some Rock Band which I hadn't played previously and Pat took the opportunity to show off his real life musical skills on the banjo.

Pat plays the banjoThis weekend, Jesse and Nicole are up visiting Seattle. On Friday, Sarah and I met up with them at the BluWater Bistro in Seattle which sits right on Lake Union. The view was nice although difficult to see from our table and overall I like the sister restaurant in Kirkland better. They were both short visits but it was fun to see people again.

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