I try to display windows explorer view as a static web page. We have to read a root folder and display all the folders and files as a static webpage. We have to use only client side programming. I know it is possible with the help of server side programming. My question is, is it possible to achieve it in front end without involving backend. I have only one problem which is reading the folder structure. How can I do it? I need to load a html file(ex..C:\workspace\treeview\index.html) in the browser and it should display all the files and folder. Also share your suggestions to achieve the above scenario?
Is there local file manipulation that's been done with JavaScript? I'm looking for a solution that can be accomplished with no install footprint like requiring .  Specifically, I'd like to read the contents from a file and write those contents to another file. At this point I'm not worried about gaining permissions and am just assuming I already have full permissions to these files.
Let $M=\big( \begin{smallmatrix} A & B \\ C & D \end{smallmatrix} \big)$. Prove $\det(M)=\det(A)\cdot \det(D-C·A^{-1}·B)$. Let  (shown in matrix blocks) $M=\big( \begin{smallmatrix} A &amp; B \\ C &amp; D \end{smallmatrix} \big)$ a square matrix such that $A$ is invertible and $D$ is a square matrix. I have to prove that  $$\det(M)=\det(A)\cdot \det(D-C·A^{-1}·B)$$  I also have an indication to use it: Consider previously these cases: \begin{align*} A_1 &amp;= \begin{pmatrix} A &amp; 0 \\ 0 &amp; I \end{pmatrix},\\ A_2 &amp;= \begin{pmatrix} I &amp; 0 \\ 0 &amp; D \end{pmatrix},\\ A_3 &amp;= A_1·A_2,\\ A_4 &amp;= \begin{pmatrix} I &amp; A^{-1}·B \\ 0 &amp; I \end{pmatrix},\text{ and}\\ A_5 &amp;= A_3\cdot A_4. \end{align*}   The problem is difficult in general for me and I don't even know how to use the indication. Showing range on hexagonal grid Here is the situation.  I have hexagonal board,and a unit on it,with speed or move value 4.Diffrent terrain has a diffrent cost.When i click on the unit,game should show me a move range.  My solution was to check each  hex in range of 4,with A* pathfinding,and if path cost was less than 4 then this hex was in range.Finally game nicely show me range of that unit.  My question is:   Is there other solution to search for range on hex grids or square grid,because even if i am really proud of what i did in my solution,i think,it is a little to exaggerated?:))  What make me ask this question?I noticed that when unit speed is 4 or 6 or even 8,time to computing range for my computer was really good,but when speed was 10 and more i noticed that i needed to wait few second to compute.Well in real games i rather dont see something like this and my A* pathfinding is rather well optimized,so im thinking that my solution is wrong.  Thanks for any replies. Precedence of user and group owner in file permissions I just ran into something unexpected (for me) regarding file permissions on Linux (Arch Linux). Basically I have:   userX in groupX fileX userX:groupX ---rwx----   What puzzles me: I cannot perform any action (rwx) on fileX. Is this right? Can someone please confirm this is indeed the expected behaviour?  The only actions I can perform are mv and rm because I have write permissions on the parent directory.  The thing is, I always thought these permissions collapse on each other, starting with the most general one (other -> group -> user). In other words, if o=rwx who cares what the persmissions for group and user are? Apparently this is not the case but it doesn't make much sense to me; it seems counterintuitive. The only thing this approach seems to be useful at, is to easily exclude a very specific person / group, which doesn't seem like a smart way to go at it (imho). Besides, the owner (and group?) should be able to chmod anyway right? Any thoughts on this matter? What exactly are the spikes, or peaks and valleys, caused by in pictures such as these    Wikipedia states that "From the point of view of magnetic energy, peaks and valleys are energetically favorable", but I'm not exactly sure what that means, or how it works. Why isn't the fluid just happy being attracted to the magnet in a semi-sphere shape? Could it be that it gains a magnetic charge, so it attempts to repel itself at the same time? Just pulling at straws here. The names of the derived functors $\operatorname{Tor}$ and $\operatorname{Ext}$ seem quite cryptic to me. Does anyone know what these abbreviations stand for? I would be glad if someone could tell me where these names come from. Series Summation,Convergence I am stuck on the 4 th one.I have done the rest.I have found out the value of a_n.But not getting how to proceed for the 4 th one. I understand that information cannot be transmitted at a velocity greater than speed of light. I think of this in terms of the radio broadcast: the station sends out carrier frequencies $\omega_c$ but the actual content is carried in the modulated wave, the sidebands $\omega_c\pm\omega_m$. The modulation envelop has its group velocity and this is the speed at which information is being transmitted. We also know, for example, that x-rays in glass have a phase velocity which is greater than the speed of light in vacuum.   My question is, what exactly is it that is travelling faster than the speed of light?    EDIT: I know it couldn't be anything physical as its superluminal. My problem is, what is it that has absolutely no information content yet we associate a velocity with it. More Efficient Spatial join in Python without QGIS, ArcGIS, PostGIS, etc I'm attempting to do a spatial join much like the example here: . However, that approach seems really inefficient / slow. Even running this with a modest 250 points takes almost 2 minutes and it fails entirely on shapefiles with > 1,000 points. Is there a better approach? I'd like to do this entirely in Python without using ArcGIS, QGIS, etc.  I'd also be interested to know if it's possible to SUM attributes (i.e. population) of all the points that fall within a polygon and join that quantity to the polygon shapefile.       Here is the code I'm trying to convert. I get an error on line 9:  poly['properties']['score'] += point['properties']['score']   which says:     TypeError: unsupported operand type(s) for +=: 'NoneType' and 'float'.    If I replace the "+=" with "=" it runs fine but that doesn't sum the fields. I've also tried making these as integers but that fails as well.  with fiona.open(poly_shp, 'r') as n:    with fiona.open(point_shp,'r') as s:     outSchema = {'geometry': 'Polygon','properties':{'region':'str','score':'float'}}     with fiona.open (out_shp, 'w', 'ESRI Shapefile', outSchema, crs) as output:         for point in s:             for poly in n:                 if shape(point['geometry']).within(shape(poly['geometry'])):                       poly['properties']['score']) += point['properties']['score'])                     output.write({                         'properties':{                             'region':poly['properties']['NAME'],                             'score':poly['properties']['score']},                         'geometry':poly['geometry']}) So in the documentation for the DescribeFieldResult.getDefaultValue , it says:     Returns the default value for this field   There is a related method called getDefaultValueFormula whose description reads:     Returns the default value specified for this field if a formula is not used.   What is the difference between these methods? I have a field with a default value. When I call getDefaultValue, I get null. When I call getDefaultValueFormula, I get back "This is the default value" (with quotes). I don't understand why getDefaultValue returns null. I understand the purpose of up/downvoting answers -- some answers are better than others, some answers may be wrong, .etc.  With regard to questions, though, there are other mechanisms to deal with "bad" questions:  comments, close, flag.  A poorly written question should be improved.  A bad question should be closed/deleted.  Often, though I see poorly written questions downvoted. I'm not sure what this accomplishes.  I get loss of rep for offensive or spam questions, but for an off-topic question?  or one that is just poorly written?   Why?  It seems to me that rep ought to be based more on answers on a site of this type.   Fundamentally, it seems that rep ought to be based on what you add to the site, not what you ask of it.  A particularly good question does add to the site, but a poor question doesn't really detract from it in the same way that a bad (wrong) answer does. Sure, go ahead and give people more rep for asking a particularly good question, but why punish people for asking bad questions when there are other ways of handling that.  Why not handle questions more like comments and allow upvotes, but not downvotes?  It seems to me that many, if not most, of the downvoted questions are first timers.  It's more likely that your first introduction to the site will be in asking a question, rather than answering. There is a significant risk to alienating new users when their questions are downvoted -- there's a visceral response to seeing that negative number next to your question.  Why not let the close/flag system weed out questions that don't belong and the comment system work to improve poorly worded questions. Average distance between two random points in a square A square with side $a$ is given. What is the average distance between two uniformly-distributed random points inside the square?  For more general "rectangle" case, see . The proof found there is fairly complex, and I am looking for a simpler proof for this special case. I expect it could be significantly simpler.  See also . Difference between JOIN and INNER JOIN Both these joins will give me the same results:  SELECT * FROM table JOIN otherTable ON table.ID = otherTable.FK   vs  SELECT * FROM table INNER JOIN otherTable ON table.ID = otherTable.FK   Is there any difference between the statements in performance or otherwise?   Does it differ between different SQL implementations? Convergence of a Harmonic Continued Fraction I'm using NetBeans, trying to change the familiar Java coffee cup icon to a png file that I have saved in a resources directory in the jar file.  I've found many different web pages that claim they have a solution, but so far none of them work.  Here's what I have at the moment (leaving out the try-catch block):  URL url = new URL("com/xyz/resources/camera.png"); Toolkit kit = Toolkit.getDefaultToolkit(); Image img = kit.createImage(url); getFrame().setIconImage(img);   The class that contains this code is in the com.xyz package, if that makes any difference.  That class also extends JFrame.  This code is throwing a MalformedUrlException on the first line.  Anyone have a solution that works? How do you pass a member function pointer? I am trying to pass a member function within a class to a function that takes a member function class pointer.  The problem I am having is that I am not sure how to properly do this within the class using the this pointer.  Does anyone have suggestions?  Here is a copy of the class that is passing the member function:  class testMenu : public MenuScreen{ public:  bool draw;  MenuButton&lt;testMenu&gt; x;  testMenu():MenuScreen("testMenu"){     x.SetButton(100,100,TEXT("buttonNormal.png"),TEXT("buttonHover.png"),TEXT("buttonPressed.png"),100,40,&amp;this-&gt;test2);      draw = false; }  void test2(){     draw = true; } };   The function x.SetButton(...) is contained in another class, where "object" is a template.  void SetButton(int xPos, int yPos, LPCWSTR normalFilePath, LPCWSTR hoverFilePath, LPCWSTR pressedFilePath, int Width, int Height, void (object::*ButtonFunc)()) {      BUTTON::SetButton(xPos, yPos, normalFilePath, hoverFilePath, pressedFilePath, Width, Height);      this-&gt;ButtonFunc = &amp;ButtonFunc; }   If anyone has any advice on how I can properly send this function so that I can use it later. Add max value to a new column in R What is the relative speed of two near-light speed particles headed towards each other? I understand that nothing can move faster than light due to time dilation. I want to build upon my understanding of Einstein's theory of Special Relativity, so I came up with this hypothetical problem for myself:  If both particles are moving at 0.9c towards each other (according to an observer on Earth), what speed does each particle have relative to the other?  I'm stumped since I am only familiar with Newtonian classical mechanics to solve this (which would be wrong). I am aware of Lorentz' factor $\gamma =\frac{1}{\sqrt{1 - \frac{v^2}{c^2}}}$ and the time dilation equation $t_m = \frac{t_o}{\sqrt{1 - \frac{v^2}{c^2}}}$, but I'm not sure how to apply it in this instance. I'm just looking for a gentle push in the right direction. Edit: My prior research:  This article, ,  talks about the effect of a baseball thrown at 0.9c would have as it traveled towards a batter. This is not what I'm looking for since it doesn't explain the math behind finding the collision speed between two high velocity entities.  This question on Yahoo, , asks a similar question to mine, but no math is involved to demonstrate the calculations behind the reasoning.  This question on Physics.SE, , does not answer my question either. I have not been able to find a similar Physics.SE question which can provide me to clues to my own hypothetical question.  I have also Googled the following phrases:    i. &quot;collision faster than the speed of light&quot; ii. &quot;collision of high speed particles&quot; iii. &quot;lorentz transformation in a collision&quot; iv. &quot;collision analysis at light speed&quot; Does a linear operator obeying Leibniz rule imply it is a differential operator? As in the title, I must prove that: If a complex function $f$ is Entire, and there exist $k,R &gt; 0$, $n \in N$ such that $|f(z)| &gt; k|z|^n$ for all $|z| &gt; R$: Then f is a polynomial.  We've already had a similar question with the inequality reversed, and found that it had to be a polynomial with degree less than n. I was able to show that if it was a polynomial, then it had to have degree less than n, but not that it had to be a polynomial in the first place.  Once again, I'm face with the same problem. I assume this time, the degree of the polynomial will have degree greater than or equal to n, but how do I show that such $f$ must be a polynomial?  It's not like I can go through every other possible function there is, can I? I can show it doesn't work for exponentials, for example, but I just can't think of how to show that this ONLY works for a polynomial... I read a YA novel in the early 2000s that I think takes place on Earth some time in the future. The human race has been enslaved by some other race, possibly aliens. If I remember correctly, humans were kept as slaves for some purpose and then exterminated at age 16, and I think some girls were kept to breed.  I remember scenes of a band of teenagers walking around sewers fighting these aliens who bled a blue "ichor." The only thing I distinctly remember about the book was that it was the first place I saw the word "ichor."  This is a pretty sorry description; but does anyone have a clue what this book was?