Javascript object traversal
How can I access and process nested objects, arrays or JSON?
How do I register a custom URL protocol in Windows? How do I register a custom protocol with Windows so that when clicking a link in an email or on a web page my application is opened and the parameters from the URL are passed to it? Shutdown and User button missing in panel I'm inserting an image with a simple:  \includegraphics[height=5cm]{filename.png}   This results in an image that maintains the aspect ratio, and so gives me something like 6cm width. I only really want the left side of the image though, and would like to crop it to 50% width. Is it possible to do this?  If possible, I'd like to do this in a portable way (i.e. something that other authors of this document won't have to install packages for, and something that works with a reasonably old version of pdflatex - our computers at work are in sore need of an upgrade). How to find out if my system is i386 or x86_64 before installing Ubuntu? I am using Windows as of now and want to install Ubuntu. I want to find out if my system is i386 or x86_64? How do I do that? Is it a good practice to show a sign-up or registration form as seperate parts rather than in one go? I am designing a registration form for a site with multiple sets of information required from the user. I have categorized the data fields into relevant groups. Now should I present the form sections in one go or follow a wizard-like approach? What things should I keep in mind while deciding on this? Are Constitution changes retroactive when calculating max HP? Lets say I'm a fighter that just leveled up to level 4, and decide to bring my Constitution up from 16 to 18. How many hit points do I have?  Level 1 = 10 (base) + 3 (Con mod) = 13.  Level 2 = 10 + 6 (average HP per fighter level) + 3 (Con mod) x 2 = 22  Level 3 = 10 + 6 (average) x 2 + 3 (Con mod) x 3 = 31  Level 4 = 10 + 6 (avg) x 3 + 3 (Con mod) x 3 (3 level-ups) + 4 (increased Con mod, which is now 4) x 1 = 41?  OR  Level 4 = 10 + 6 (avg) x 3 + 4 x 4 (4 times current Con mod) = 44?  If it's the first option, it's simply better to level Constitution up at earlier levels. The Civilization series of games is famous for having a way to play by e-mail. This allows people to take a long time on their turn without holding up the other players, as you do in a real-time game. Yet, I can not find any method to play by e-mail in the game menus. Does it exist? If so, how do you do it? How to Start Web Mapping? I want to start working on a web map at work to map some of our statistics by city.    I have an idea, but I'm not exactly sure where to start.   Are there any definitive resources that provide step by step guidance on how to do this? The thing with these tags is, you can always (or almost always) use a specific product/technology/language tag which would render the company-name tag completely redundant (see Appendix C for sloppy non-proof). For example, what relevant information would  tag add to  already tagged with ? What would  tag add to  already tagged with ? Another way of looking at this: how much useful information do you lose if you don't tag a question with a company name? Note: I'm not talking about brand/company/organizations like , , ,  because those names also refer to websites/web services with which you can interact via API or from which you can extract data. Appendix C: The &quot;about&quot; test The relationship between a tag and a question can be expressed as such  This question is about [tag]  In case of ,  This question is about [microsoft]  Fair enough. But in reality people are using these company-name tags like this  This question is about something developed by or related to [microsoft]  But if that's the case, you might as well just go with  This question is about [something developed by or related to microsoft]  where  can be , , ... you get the idea. Derivative of determinant of a matrix I would like to know how to calculate:  $$\frac{d}{dt}\det \big(A_1(t), A_2(t), \ldots, A_n (t) \big).$$ How can I grep in PDF files? Is there a way to search PDF files using grep, without converting to text first in Ubuntu? How do I setup user autostart and properly configure systemd user services? On my arch server, I was setting up users restricted to their home directories. I ran:  useradd -m -s /bin/bash username and passwd username  I've read   I figured I should use systemd user services to make each user run a node server on startup. So i logged into one user account su username and created a file ~/.config/systemd/user/serve.service containing:  [Unit] Description=One of the servers  [Service] ExecStart=/usr/bin/node /home/username/server.js  [Install] WantedBy=default.target   then I ran systemctl --user enable serve.service which responded with Failed to connect to bus: Permission denied  As far as I understand I should run systemctl --user ... command logged in as a user and not as root.  So what did I miss in this configuration? Sorry for the title, its hard to put the problem into proper words.  Basically, in Firefox or Chrome, I try to navigate to stackoverflow.com.  The request fails and the URL I see in the navigation bar is:  http://d2e24t2jgcnor2.webhostoid.com/Secure/Error?URL=http%3A%2F%2Fstackoverflow.com%2F&amp;ResponseCode=504&amp;user_id=5b5033d3-3543-4b7c-9844-055afde93841&amp;uc=20140915&amp;subid=20140915&amp;source=browsersafeguard-rockettab-spigot&amp;version=1.0.5370.12627&amp;implementation_id=browsersafeguard-rockettab-spigot%20&amp;block_host=False&amp;reg=False&amp;redirectms=True   This looks shady and my internet seems slower lately. I have a few questions:   Why is my request going through this strange URL? Do the query parameters reveal my identity? How can I stop this?   I use my cell phone’s 3G network and tether it to my laptop. Proving Binomial Identity without calculus How to establish the following identities without the help of calculus:  For positive integer $n, $ $$\sum_{1\le r\le n}\frac{(-1)^{r-1}\binom nr}r=\sum_{1\le r\le n}\frac1r $$  and  $$\sum_{0\le r\le n}\frac{(-1)^r\binom nr}{4r+1}=\frac{4^n\cdot  n!}{1\cdot5\cdot9\cdots(4n+1)}$$ I am trying to design a circuit and was wondering how to design it that the 12V 800mAH NimH battery I am using will not overcharge. I have researched trickle charging and as far as I understand, a zener diode that regulates the voltage down to about 13.3-13.7V should do. I chose a 14V Zener, taking into account the .6-.7V drop.   I have heard that trickle charging is not the best for the battery, but am not sure how much more work designing a smart charger would take.  I was also thinking of using another diode to prevent flow back to the panels from the battery.         &ndash; Schematic created using  The three voltage sources on the left represent the solar cells, with the NiMH battery on the right.  I was wondering if I needed any additional components if I were to use three 5.5V solar cells in parallel outputting 40mA (16.5V total at 40mA, regulated to 13.3V by the zener) in order to prevent overcharging.  A similar question to mine was asked at  However, this dealt more with a larger lead-acid battery and used a voltage regulator with a schottky diode.   This link discusses almost my exact same question, but I was confused to the answer given which said that up to 1.45V per cell could be charged, taking my max charge voltage up to 14.5V.   Considering I am only outputting 40mA to an  800mAH battery, it seems that I may not need any more battery protection, but would love any input. How to diagnose computer lockups and freezes? "To shoot out of cannon into sparrows" In Russian we have idiom/saying "To shoot out of cannon into sparrows" (literal translation) which is used to convey an idea of applying too drastic measures to small problems. I believe there should be some native-English equivalents to this saying. Can you share if there are any? Capacity of pen drive shown is less than the actual I have a 8 GB pendrive. I used to write raw data into the pendrive (without creating filesystem) using the dd command.    Today, when I inserted the pen drive, the I am unable to write anything on to it.  When I open gparted it is showing the total space on the pen drive as 500 MB. I am unable to create a new partition table or a partition on the pen drive now.   Here is the fdisk -l output.   Disk /dev/sdb: 0 MB, 512000 bytes 255 heads, 63 sectors/track, 0 cylinders, total 1000 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 4096 bytes I/O size (minimum/optimal): 4096 bytes / 4096 bytes Disk identifier: 0x00095df6   What's wrong with the pen drive? How can I recover the lost space?   Device Boot      Start         End      Blocks   Id  System   When I open gnome-disks, it shows the total space as 8 GB but when I try to create a new partition using it, it shows the following error:  Error creating partition on /dev/sdb: Command-line parted --align optimal --script "/dev/sdb" "mkpart primary ext2 1MiB 7969177599b"' exited with non-zero exit status 1: Error: The location 7969177599b is outside of the device /dev/sdb.  (udisks-error-quark, 0) Will the Lee 100mm filter holder work with a Samyang 14mm autofocus lens? Will this  work with a ? Which adapter ring would I need to buy for it? Thank you, and apologies if any of this comes across as confusing - I'm very new to filters and what-not. I posted on another account yesterday and received some very useful tips, but had to remove it as it was a duplicate account causing me login issues. Thanks, guys! Label legend interval with number of elements in ArcMap? I have made a series of  in ArcMap 10. When I classify the interval the bottom of the dialogue tells how many elements are in the class.  Is it possible to have this number automatically places beside my class labels?