Below is my object in JavaScript, how can i calculate the length of it.   var treeObj = {             1: ['96636736','10'],             2 : ['96636734','20'],             3 : ['96636731','45']               };       treeObj .length is not working. any help would be appreciated. Thanks.
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I have a JavaScript object. Is there a built-in or accepted best practice way to get the length of this object? const myObject = new Object(); myObject[&quot;firstname&quot;] = &quot;Gareth&quot;; myObject[&quot;lastname&quot;] = &quot;Simpson&quot;; myObject[&quot;age&quot;] = 21;
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What is the best way to check whether a given object is of a given type? How about checking whether the object inherits from a given type?  Let's say I have an object o. How do I check whether it's a str?
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I know that in JavaScript, creating a for loop like this: for(int i = 0; i &lt; arr.length; i++) is costly as it computes the array length each time. Is this behavior costly in c# for lists and arrays as well. Or at compile-time is it optimized?  Also what about other languages such as Java, how is this handled?
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Is the memory space consumed by one object with 100 attributes the same as that of 100 objects, with one attribute each?  How much memory is allocated for an object? How much additional space is used when adding an attribute?
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I am trying to add key value pair in the below JSON object, but it is getting added in the wrong way, is there any way i can add to each object a new  key value pair, that will help me to complete the req. JSON as follow : var object =[       {          &quot;asdf&quot;:&quot;&quot;,          &quot;fdrtf&quot;:&quot;869966&quot;,          &quot;hdhfhfh&quot;:&quot;utytut&quot;,          &quot;Cat&quot;:&quot;A&quot;                 },       {          &quot;hjhj&quot;:&quot;&quot;,          &quot;hfhfhf&quot;:&quot;h&quot;,          &quot;hhfh&quot;:&quot;hfjfhdj&quot;,          &quot;cat&quot;:&quot;B&quot;                 },       {          &quot;hjhj&quot;:&quot;&quot;,          &quot;hfhfhf&quot;:&quot;h&quot;,          &quot;hhfh&quot;:&quot;hfjfhdj&quot;,          &quot;cat&quot;:&quot;B&quot;       } ]  code i am using to add the new key value pair : for (let i = 0; i &lt; object.length; i++) {             object[i]['ABC'] = [i];         }  Actually expected should be: var object =[       {          &quot;asdf&quot;:&quot;&quot;,          &quot;fdrtf&quot;:&quot;869966&quot;,          &quot;hdhfhfh&quot;:&quot;utytut&quot;,          &quot;Cat&quot;:&quot;A&quot;,          &quot;ABC&quot;: &quot;0&quot;                 },       {          &quot;hjhj&quot;:&quot;&quot;,          &quot;hfhfhf&quot;:&quot;h&quot;,          &quot;hhfh&quot;:&quot;hfjfhdj&quot;,          &quot;cat&quot;:&quot;B&quot;,          &quot;ABC&quot;: &quot;1&quot;                 },       {          &quot;hjhj&quot;:&quot;&quot;,          &quot;hfhfhf&quot;:&quot;h&quot;,          &quot;hhfh&quot;:&quot;hfjfhdj&quot;,          &quot;cat&quot;:&quot;B&quot;          &quot;ABC&quot;: &quot;2&quot;       } ]  the final value i am getting as below: [&quot;0&quot;:{          &quot;hjhj&quot;:&quot;&quot;,          &quot;hfhfhf&quot;:&quot;h&quot;,          &quot;hhfh&quot;:&quot;hfjfhdj&quot;,          &quot;cat&quot;:&quot;B&quot;,           },    &quot;1&quot;:{          &quot;asdf&quot;:&quot;&quot;,          &quot;fdrtf&quot;:&quot;869966&quot;,          &quot;hdhfhfh&quot;:&quot;utytut&quot;,          &quot;Cat&quot;:&quot;A&quot;              },    &quot;2&quot;:{        &quot;hjhj&quot;:&quot;&quot;,          &quot;hfhfhf&quot;:&quot;h&quot;,          &quot;hhfh&quot;:&quot;hfjfhdj&quot;,          &quot;cat&quot;:&quot;B&quot;    }   ]  kindly someone help me out to achieve this
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I'm not that into dynamic programming languages but I've written my fair share of JavaScript code. I never really got my head around this prototype-based programming, does any one know how this works? var obj = new Object(); obj.prototype.test = function() { alert('Hello?'); }; var obj2 = new obj(); obj2.test();  I remember a lot discussion I had with people a while back (I'm not exactly sure what I'm doing) but as I understand it, there's no concept of a class. It's just an object, and instances of those objects are clones of the original, right? But what is the exact purpose of this &quot;.prototype&quot; property in JavaScript? How does it relate to instantiating objects? Update: correct way var obj = new Object(); // not a functional object obj.prototype.test = function() { alert('Hello?'); }; // this is wrong!  function MyObject() {} // a first class functional object MyObject.prototype.test = function() { alert('OK'); } // OK  Also these  really helped a lot.
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For example: sizeof(char*) returns 4.  As does int*, long long*, everything that I've tried.  Are there any exceptions to this?
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How do I trim a string in JavaScript? That is, how do I remove all whitespace from the beginning and the end of the string in JavaScript?
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First off, here is some code:  int main()  {     int days[] = {1,2,3,4,5};     int *ptr = days;     printf("%u\n", sizeof(days));     printf("%u\n", sizeof(ptr));      return 0; }   Is there a way to find out the size of the array that ptr is pointing to (instead of just giving its size, which is four bytes on a 32-bit system)?
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Do you think there is a big difference in for...in and for loops? What kind of "for" do you prefer to use and why?  Let's say we have an array of associative arrays:  var myArray = [{'key': 'value'}, {'key': 'value1'}];   So we can iterate:  for (var i = 0; i &lt; myArray.length; i++)   And:  for (var i in myArray)   I don't see a big difference. Are there any performance issues?
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When {0} is used to initialize an object, what does it mean? I can't find any references to {0} anywhere, and because of the curly braces Google searches are not helpful.  Example code:  SHELLEXECUTEINFO sexi = {0}; // what does this do? sexi.cbSize = sizeof(SHELLEXECUTEINFO); sexi.hwnd = NULL; sexi.fMask = SEE_MASK_NOCLOSEPROCESS; sexi.lpFile = lpFile.c_str(); sexi.lpParameters = args; sexi.nShow = nShow;  if(ShellExecuteEx(&amp;sexi)) {     DWORD wait = WaitForSingleObject(sexi.hProcess, INFINITE);     if(wait == WAIT_OBJECT_0)         GetExitCodeProcess(sexi.hProcess, &amp;returnCode); }   Without it, the above code will crash on runtime.
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Object o = new Long[0] System.out.println( o.getClass().isArray() ) System.out.println( o.getClass().getName() ) Class ofArray = ???   Running the first 3 lines emits;  true [Ljava.lang.Long;   How do I get ??? to be type long?   I could parse the string and do a Class.forname(), but thats grotty.   What's the easy way?
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What's the fastest way to count the number of keys/properties of an object?  It it possible to do this without iterating over the object?  i.e. without doing  var count = 0; for (k in myobj) if (myobj.hasOwnProperty(k)) count++;   (Firefox did provide a magic __count__ property, but this was removed somewhere around version 4.)
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How is parseInt() different from valueOf() ?   They appear to do exactly the same thing to me (also goes for parseFloat(), parseDouble(), parseLong() etc, how are they different from Long.valueOf(string) ?  Also, which one of these is preferable and used more often by convention?
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How do I remove all attributes which are undefined or null in a JavaScript object?  (Question is similar to  for Arrays)
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The function  should calculate distances between two points.  When I am trying to calculate distance between points having 100 meters between them  p1=new esri.geometry.Point(3997030.6690969253, 7444299.320646087, new esri.SpatialReference({ wkid: 102113 })); Object p2=new esri.geometry.Point(3996951.455397143, 7444142.154020177, new esri.SpatialReference({ wkid: 102113 })); Object esri.geometry.getLength(p1, p2) 176.00045037719127   I am getting 176 which is wrong. Projection is Web Mercator (WKID 102113).    @Krystian found that getLength uses just Pythagoras theorem to calculate length. So it gives length in projection meters. How to obtain distance in real meters?
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I'm pulling items out of the DOM with jQuery and want to set a property on an object using the id of the DOM element.   Example  const obj = {}  jQuery(itemsFromDom).each(function() {   const element = jQuery(this)   const name = element.attr('id')   const value = element.attr('value')    // Here is the problem   obj.name = value })   If itemsFromDom includes an element with an id of "myId", I want obj to have a property named "myId". The above gives me name.  How do I name a property of an object using a variable using JavaScript?