Setting an object property to undefined On Chrome's and Node's console, I assigned the property of an object to have the value of undefined.  const foo = {   bar: undefined };   When I evaluate foo again, I expected it to give me an empty object ({}), but it returns with:  {   bar: undefined }   Are there any differences between { bar: undefined } and {}?  The reason I am asking is that this difference is failing my tests - I am expecting the result to be {}, but it's failing because the actual response is { bar: undefined }.  If it was { bar: null } I'd understand, since null is an actual value. But my understanding is that undefined means the property is undefined and thus not even a value.
How do I remove a property from a JavaScript object? Say I create an object as follows: let myObject = {   &quot;ircEvent&quot;: &quot;PRIVMSG&quot;,   &quot;method&quot;: &quot;newURI&quot;,   &quot;regex&quot;: &quot;^http://.*&quot; };  How should I remove the property regex to end up with new myObject as follows? let myObject = {   &quot;ircEvent&quot;: &quot;PRIVMSG&quot;,   &quot;method&quot;: &quot;newURI&quot; };
What does it mean if a Python object is "subscriptable" or not? Which types of objects fall into the domain of "subscriptable"? So I have an SQL dump file that needs to be loaded using mysql_query(). Unfortunately, it's not possible to execute multiple queries with it.  -> It cannot be assumed that the mysql command-line client (mysql --help) is installed -- for loading the SQL file directly  -> It cannot be assumed that the mysqli extension is installed  /* contents of dump.sql, including comments */ DELETE FROM t3 WHERE body = 'some text; with semicolons; scattered; throughout'; DELETE FROM t2 WHERE name = 'hello'; DELETE FROM t1 WHERE id = 1;   The explode() below won't work because some of the dump content's values contain semicolons.  $sql = explode(';', file_get_contents('dump.sql')); foreach ($sql as $key =&gt; $val) {     mysql_query($val); }   What's the best way to load the SQL without modifying the dump file? Slovak (and Czech) babel gives problems with cmidrule and cline I tried to use the Slovak language with the booktabs package.    Let's see a couple of cases.   slovak is included in the options to babel     \usepackage[english,slovak]{babel}   or    \usepackage[slovak,english]{babel}   or    \usepackage[slovak]{babel}`  "slovak" is NOT included in the options to babel  \usepackage[english]{babel}    Similarly two cases for \cmidrule  A. \cmidrule{2-3} is included in the table    B. \cmidrule{2-3} is NOT included in the table    If both (slovak+\cmidrule) are included (case 1A), then following error occurrs  Paragraph ended before \@@@cmidrule was complete   (and a lot of other errors)  In the other cases (1B, 2A and 2B) (NO slovak or NO \cmidrule), then pdflatex is succesful  Does anybody know why 1A is wrong?    And how to use slovak and \cmidrule together (case 1A)?  \documentclass[10pt]{book} \usepackage[english,slovak]{babel} \usepackage{booktabs}  \begin{document}  \begin{tabular}{ccc} A &amp; B &amp; C \\ %\cmidrule{2-3} A &amp; B &amp; C \\ \end{tabular}  \end{document}   I have Win7, TeXstudio 2.5.2 This or That person Make program first read from pipe, then from keyboard Acer Aspire E15 will not dual boot I installed Ubuntu 14.04 onto my Acer Aspire E15. The PC has a 500 Gigabyte HDD.   During the installation it divided the HDD into separate partitions. However every time I turn on the PC it goes directly into Windows 8.1. It doesn't allow you the opportunity to select which OS you want to use.   Question 1: How do I set the PC so it will allow me to select the OS?  Question 2: And if #1 isn't possible. How to I remove Ubuntu from the PC and recover the partition for Windows I asked a  on stackoverflow at the end of last year for a beta or pre-release product and got the answer I wanted.  3 months later someone else answered the question with the correct answer for a newer release.  This answer got way more upvotes than the one I accepted.  I only noticed this today so changed the accepted answer.  Can I get a notification email when an answer gets say 10 more votes than the one I accepted.  Just to let me know something might be up. I am using VC++. Is assert(false) ignored in release mode? I want to apply for Schengen visa, but employer NOC which is mandatory document for visa is not available with me I have resigned from my current company and will be joining a new company soon.   Hence, I cannot get a leave approval letter from my current company, and if I decide to join a new company and then request a NOC (No Objection Certificate) it will be late for visa process completion because of my traveling dates.   What can I show to the embassy as an alternative to this NOC document? LaTeX template for typesetting a novel I'd like to use LaTeX to typeset a novel. Could you recommend me any template?  What I mean is a template (some .tex file) where I can include my chapterN.tex files (mainly plain text) and get a pretty good design with zero work :) German language: use of comma in numbers I am trying to fit a SVM to my data. My dataset contains 3 classes and I am performing 10 fold cross validation (in LibSVM):   ./svm-train -g 0.5 -c 10 -e 0.1 -v 10 training_data   The help thereby states:  -c cost : set the parameter C of C-SVC, epsilon-SVR, and nu-SVR (default 1)   For me, providing higher cost (C) values gives me higher accuracy. What does C in SVM actually mean? Why and when should I use higher/lower values (or the LibSVM given default value) of C? Drawing simple edge, no arrow I have  \begin{tikzpicture}[-&gt;,auto,node distance=3cm,   thick,main node/.style={draw,font=\bfseries}]   \node[main node] (111) at (0,1) {$X_{1,1}^{(1)}$};   \node[main node] (121) at (0,2) {$X_{1,2}^{(1)}$};   \node[main node] (1n1) at (0,4) {$X_{1,n}^{(1)}$};   \node[main node] (211) at (0,6) {$X_{2,1}^{(1)}$};   \node[main node] (221) at (0,7) {$X_{2,2}^{(1)}$};   \node[main node] (2n1) at (0,9) {$X_{2,n}^{(1)}$};   \node[main node] (n11) at (0,11) {$X_{n,1}^{(1)}$};   \node[main node] (n21) at (0,12) {$X_{n,2}^{(1)}$};   \node[main node] (nn1) at (0,14) {$X_{n,n}^{(1)}$};   \node[main node] (112) at (2.5,1) {$X_{1,1}^{(2)}$};   \node[main node] (122) at (2.5,2) {$X_{1,2}^{(2)}$};   \node[main node] (1n2) at (2.5,4) {$X_{1,n}^{(2)}$};   \node[main node] (212) at (2.5,6) {$X_{2,1}^{(2)}$};   \node[main node] (222) at (2.5,7) {$X_{2,2}^{(2)}$};   \node[main node] (2n2) at (2.5,9) {$X_{2,n}^{(2)}$};   \node[main node] (n12) at (2.5,11) {$X_{n,1}^{(2)}$};   \node[main node] (n22) at (2.5,12) {$X_{n,2}^{(2)}$};   \node[main node] (nn2) at (2.5,14) {$X_{n,n}^{(2)}$};   \node[main node] (11k) at (6,1) {$X_{1,1}^{(k)}$};   \node[main node] (12k) at (6,2) {$X_{1,2}^{(k)}$};   \node[main node] (1nk) at (6,4) {$X_{1,n}^{(k)}$};   \node[main node] (21k) at (6,6) {$X_{2,1}^{(k)}$};   \node[main node] (22k) at (6,7) {$X_{2,2}^{(k)}$};   \node[main node] (2nk) at (6,9) {$X_{2,n}^{(k)}$};   \node[main node] (n1k) at (6,11) {$X_{n,1}^{(k)}$};   \node[main node] (n2k) at (6,12) {$X_{n,2}^{(k)}$};   \node[main node] (nnk) at (6,14) {$X_{n,n}^{(k)}$};   \node[main node] (11n2) at (9.5,1) {$X_{1,1}^{(n-2)}$};   \node[main node] (12n2) at (9.5,2) {$X_{1,2}^{(n-2)}$};   \node[main node] (1nn2) at (9.5,4) {$X_{1,n}^{(n-2)}$};   \node[main node] (21n2) at (9.5,6) {$X_{2,1}^{(n-2)}$};   \node[main node] (22n2) at (9.5,7) {$X_{2,2}^{(n-2)}$};   \node[main node] (2nn2) at (9.5,9) {$X_{2,n}^{(n-2)}$};   \node[main node] (n1n2) at (9.5,11) {$X_{n,1}^{(n-2)}$};   \node[main node] (n2n2) at (9.5,12) {$X_{n,2}^{(n-2)}$};   \node[main node] (nnn2) at (9.5,14) {$X_{n,n}^{(n-2)}$};   \node[main node] (11n1) at (12,1) {$X_{1,1}^{(n-1)}$};   \node[main node] (12n1) at (12,2) {$X_{1,2}^{(n-1)}$};   \node[main node] (1nn1) at (12,4) {$X_{1,n}^{(n-1)}$};   \node[main node] (21n1) at (12,6) {$X_{2,1}^{(n-1)}$};   \node[main node] (22n1) at (12,7) {$X_{2,2}^{(n-1)}$};   \node[main node] (2nn1) at (12,9) {$X_{2,n}^{(n-1)}$};   \node[main node] (n1n1) at (12,11) {$X_{n,1}^{(n-1)}$};   \node[main node] (n2n1) at (12,12) {$X_{n,2}^{(n-1)}$};   \node[main node] (nnn1) at (12,14) {$X_{n,n}^{(n-1)}$};   \path     (111) edge (112)         edge (122)         edge (1n2)     (121) edge (112)         edge (122)         edge (1n2)     (1n1) edge (112)         edge (122)         edge (1n2)     (121) edge[--,dashed] (1n1); \end{tikzpicture}   I just want simple lines, no arrows. How to manage with edge to achieve that? Thanks I accidentally installed some USB drivers to my Windows 7 system, they were the wrong ones and now my keyboard and mouse won't work. A system restore would get rid of them, but obviously I can't control my computer to make that happen.  Keyboard and mouse still work before windows has loaded, in the BIOS and boot system, so can I do anything from there? I've already tried booting into another OS, accessing my windows filesystem and deleting the Program Files entry, but it didnt work so they must go deeper than that. Or could i launch it from a remote machine? I've got some VNC server insalled so if i could get that running that could work. Program to create EMF that conserves transparency What open source tools allow for the creation of EMFs that conserve transparency in ArcMap?  I tried VeryPDF and Any DWG to Image Converter, neither on actually gave me a vector file that provided transparency.  Adobe Illustrator is a bit pricey when all I want to do is convert CAD blocks to vector symbols to use as ArcMap markers.  Anyone know of a good software for this purpose? How long do you get to use a UK standard visitor visa from time of issue or is it valid for entry indefinite I am going to apply for a standard visitor visa for my girlfriend to enter UK. If it is issued how soon does it have to be used after issue, ie. validity until time of entry? Correct way to render crepuscular rays in cycles? While trying to use the new cycles volumetric rending features to create  (with the intention of updating ), I have found this to be a little trickier than I anticipated.    When I create a basic setup with a spot lamp (sun lamps don't seem to work, not sure if that is a result of their one directional nature or what..) and a world material like this:    Which gives me this (500 samples):    The problems with this that make me think that I'm missing something (aside from the rendertime and noise, which I understand to be a part of using bleeding edge new features) are:   The background shader/sky texture isn't visible at all (volume is too dense?) The lamp needed to be set to 50000 strength (this is of course dependent on the distance from the camera, but the kinds of strengths required to get some nice defined rays will blow everything out if volumes are disabled)   I can't seem to get a straight render (no compositing tricks) to look anything remotely like the pretty image in the release notes:        (source: )     Is this just how it works? Or is there some trick I have missed (not counting compositing/renderlayer tricks)? Windows 8 hibernation option missing from power options Windows 8 Professional 32-bit running on Laptop. And the Hibernation option is missing from the Power Options in the System Settings. Even after I enable hidden power features by giving admin privileges.  How can I fix this?    Also the option to enable hibernation is missing from the advanced power plan options.      SOLUTION UPDATE:  Thanks to  I have found that you need to enable hibernation using a command prompt.   Get to the Start menu, type 'CMD' this will begin the search. Press the CTRL+SHIFT+ENTER to start the command prompt with administrative privileges. Type powercfg -h on and press enter Are drops in Google ranking common after switching to https? About a week ago I made the switch to https on one of my sites. I'm positive I did everything right. Properly setup 301 redirects from http to https versions. Added and verified https version in Webmaster Tools. Updated all internal links. Submitted new sitemap.  Despite that, many of my pages (about 40%) lost their rankings almost immediately. Those that dropped went from page 1 to nowhere. I can still see them indexed if I search for the URL, but otherwise it's like Google doesn't know they exist.  SSL Labs shows an "A" when I run their test and I have no manual actions showing in Webmaster Tools.  This is really frustrating. I don't actually need SSL, but Google finally scared me into it. Now I'm regretting the switch and contemplating going back to non-secured URLs.  Anything else I could have missed? Why is gksu no longer installed by default? I have always recommended pressing ALT+F2 and typing for example gksu nautilus or gksudo nautilus both are equivalent; to run graphical programs with root privileges.  However, I have just installed raring on a test system and this no longer works.  gksu and gksudo are not installed as part of a default raring install; though they are in the repositories. In 12.04 at least gksudo was just a symbolic link to gksu  The reasons I have always done this are because while it is often safe to use sudo under some circumstances it can cause problems with graphical applications because gksu has you running the program as root while with sudo you are running as yourself but with elevated privileges.  This can mean you inadvertently change the owner of critical system files.  This can cause problems.  This reasoning is explained better here:         Why was command removed from a fresh install and what should we be using instead?