How to create an object property from a variable value in JavaScript?
Add a property to a JavaScript object using a variable as the name?
say by has the meaning of      6. indicating the period in which something happens: ‘this animal always hunts by night’   Then do we need to say, ‘Why does the sky glitter by night?’ And can’t we say, ‘Why does the sky glitter at night?’?   If we can use both, what’s the difference between the two? How can I safely prototype a mains power circuit? I'm building a device that has a mains power component, which I need to prototype before building to make sure everything works. I know I need to make sure wiring—and insulation!—is thick enough to cope with the higher current, and that I need to make sure there's enough space between exposed components so there's no arcing. I'll also be stashing whatever I prototype in a nice, insulated box before applying power, and I'll be include a small-value (250mA) fuse just in case. I'll be considering everything double-insulated rather than earthed (plastic enclosure, and there's nothing I'll need to touch while it's operating).  My plan is to solder (through-hole) components directly to each other, then insulate everything (with heatshrink tubing or electrical tape) as much as possible, then use screw-type cable joiners to connect the power cable.  I know I can't use traditional prototyping tools such as breadboards and stripboard for mains voltages, but what can I use to make prototyping at mains voltages easier?  (To be clear, 'mains voltage' in my area means 230V AC +10/-6% at 50Hz; GPOs are generally rated at 10A.) What are the general rules regarding when can you refreeze food that was frozen and then thawed in the fridge? and what are the reasons behind them? (Hygiene? Food quality?). Let's assume for the sake of the argument that the items were in a non-frozen state only a few hours.  To be more specific, I'm interested in the application of these rules for  - Ginger garlic paste - Dough - Indian Curries - Green Chilly paste - Frozen green peas Evaluating the integral $\int_0^{\frac{\pi}{2}}\log\left(\frac{1+a\cos(x)}{1-a\cos(x)}\right)\frac{1}{\cos(x)}dx$ Does this answer your question? Notice remains open even after submitting feedback How do we see? Where do the photons disappear? I know that the light is reflected from a object to my eyes, but I don't understand exactly how. The photons appear from the light source and disappear in my eye! Can someone explain the phenomenon of where the photons go and do to allow us to see? Why does this stream return no element? Algorithms for computing multiplicative order modulo $n$ Why do cockroaches burst from soapy water? making low-quality PDF files clearer Some research papers available on the web have low-quality outputs. For example, see . It seems that it was converted from a PS file and typeset in (La)TeX. However, it has all the font information. Is there any way to make the PDF file clearer? Please don't refer to 2019 as 'a great year' This is one of the possible ways I come out:  struct RetrieveKey {     template &lt;typename T&gt;     typename T::first_type operator()(T keyValuePair) const     {         return keyValuePair.first;     } };  map&lt;int, int&gt; m; vector&lt;int&gt; keys;  // Retrieve all keys transform(m.begin(), m.end(), back_inserter(keys), RetrieveKey());  // Dump all keys copy(keys.begin(), keys.end(), ostream_iterator&lt;int&gt;(cout, "\n"));   Of course, we can also retrieve all values from the map by defining another functor RetrieveValues.  Is there any other way to achieve this easily? (I'm always wondering why std::map does not include a member function for us to do so.) Why does DMM show AC and DC current when source is a battery? (How to calculate power in this case?) The circuit is an altered Joule Thief of my design that is driven by an AA or AAA battery. I’m observing the current at the battery anode with my DMM in series. (Extech EX330) This circuit is extremely efficient (In relation to other Joule Thief I've build.) and does some weird stuff - like, it needs a pushbutton sometimes.    Measurements: It is drawing 9.21 mA DC and 6.48 mA AC in series with the battery. It shows 1.364 VDC and 0.010 VAC in parallel with the battery. Output on the LED is 2.572 VDC and 0.011 VAC with no measurable frequency. (with my DMM at least) All measurements are taken with the same configuration and voltage.    But how is it drawing AC and DC and how do I calculate power consumption? --> Could it be because the emitter pin of the NPN is directly connected to ground? --> Or is the circuit just "switching on and off"?     Download schematic:  (I tried to simulate the circuit in LTspice. Thanks for making me aware of this amazing program, Sredni Vashtar!)     What the pushbutton is used for: The pushbutton is used to "kickstart" the oscillation when it wont start by itself. For example: I have to manually "oscillate" using this button to start the circuit if the capacitor is too big and battery voltage is low. Pushing the button releases the energy in the transformer into the capacitor. If it reaches LED forward voltage the circuit keeps oscillating on it's own. It does work without manual intervention when then capacitor in parallel with the LED is not too big, like &lt;5000 µF, and it's a fresh battery.    . Thank you for your answers! I'm learning so much! :D How to get new answers to old/popular questions read/voted on? If a question has more than one page of answers then a new answer is not likely to get much attention.  I think the stackoverflow engine should give some more weight to newer answers to old questions but I'm not sure how.  Maybe a tweaked UI to get access to newer answers.  NB. In the related questions this  popped up, I hadnt realised either that these tools existed. Dimensional Tolerance for US Standard NEMA 1-15 Plugs I am trying to find the dimensional tolerance on US electrical plugs. I have tried looking online, but I have only been able to find that they are called , and have found the picture below showing length and height for the male connector (but not width of the male prong), and I haven't been able to find dimensional tolerances anywhere.     I ask here because I'm assuming there's a US code that governs electrical plugs, but I can't seem to find the standard anywhere. Why gravity is an attractive force? Why gravity is an attractive force?     One may say that it is because of space time curvature but General Relativity is built on this law: $\displaystyle G \frac{m_1 \times m_2}{r^2}$ (To be more precise, it is  from it's potentiel form known as  that can be written like this: $\nabla \cdot g = - 4\pi Gp  $). So GR can't explain why gravity is attractive. General Relativity only explains how gravity occurs in terms of space time.    Another may stick with the Quantum theory stating that gravitons are responsible for the force of gravity, but why a massless particle with spin 2 will exchange positive momentum? Novel(s) based on humanity fleeing from Earth and regressing to a pre-industrial state on a Colony so as to escape detection Shortly before his death, my father spoke to me about a series of novels that he had just finished reading which had a fascinating concept.  However I soon forgot the title(s) and author and I've been absolutely desperate to find out what they were.  The premise (as I understood) was that humanity had expanded out from the solar system into the local star systems before coming into contact with an incredibly aggressive species which was focused on wiping out the entire species.  Earth and her colonies were lost as remnants of the species fled.  Eventually it was decided by the military leadership to set up a colony in order to rebuild the human race.  However, in order for this colony to escape detection and to keep humanity from going back out into space and thus potentially running into this hostile alien race again, a series of satellites were set up around the planet chosen that would lock onto and destroy any form of technology (and usually the surrounding city) that went beyond pre-industrial standards.    One of the series protagonist is a long living android who possesses the consciousness of a human who was present at the original founding of the colony (and who seems shielded from detection) which observes as civilization is repeatedly regrown and torn down again and who attempts to try and reverse humanities self imposed lot in life.      From what I understood this was a series of novels, but I could be wrong. I've been trying to find this for years on my own with only a rough plot line as a guide and it's gotten me nowhere. How to remove comma between taxonomy terms? I style my taxonomy terms as boxes, so I don't need comma between them.  Could somebody give me any advice? Could someone give an example of a ‘very’ discontinuous derivative? I myself can only come up with examples where the derivative is discontinuous at only one point. I am assuming the function is real-valued and defined on a bounded interval. Notify on retagging A question here on meta for instance may stick around for quite a while. A feature-request  maybe even for months. Then the status (tags) gets changed to  or  or whatever and the OP does not get notified.  On a normal post-edit we get a notification but retagging does not count for that. Please add retagging to the edit notifications.