this

I'm a beginner to closures (and Javscript in general), and I can't find a satisfactory explanation as to what's going on in this code: function myObject(){ this.myHello = "hello"; this.myMethod = do_stuff; } function do_stuff(){ var myThis = this; $.get('http://example.com', function(){ alert(this.myHello); alert(myThis.myHello); }); } var obj = new myObject; obj.myMethod(); It will alert 'undefined' and then 'hello'. Obviously this should not be jQuery specific, but this is the simplest form of my original code I could come up with. The closure in do_stuff() has access to the variables in

What is receiver parameter in Java ? Java 8 Language Specification talks about this . The JLS gives a hint : Either way, the receiver parameter exists solely to allow the type of the represented object to be denoted in source code, so that the type may be annotated. These two methods are equivalent: class Test { void m1() { } void m2(Test this) { } } However the latter allows you to add annotations: void m2(@MyAnnotation Test this) { } //where MyAnnotation can be defined like this for example: @Target(ElementType.TYPE_USE) @interface MyAnnotation {} Debasis Receiver parameters allow to pass

In this blog author says below function is a constructor function : function Cat(name, color) { this.name = name; this.color = color; } Cat.prototype.age = 0; var catC = new Cat("Fluffy", "White"); The instances of Cat function has a name and colour property. Is this the only difference between normal and constructor function? A constructor function is a normal function. What makes the difference here is the use of the new operator which makes the context ( this ) in the function the new instance, thus letting it take the two properties, and returns this new instance. Without the new operator,

Advanced title, simple question: How can I do the following in jQuery (hiding everything except $(this) )? $("table tr").click(function() { $("table tr:not(" + $(this) + ")").hide(); // $(this) is only to illustrate my problem $("table tr").show(); }); $(this).siblings().hide(); Traversing/Siblings $("table.tr").not(this).hide(); As an aside, I think you mean $("table tr") (with a space instead of a dot). The way you have it, it selects every table which has a class of tr (eg, <table class="tr"> ), which is probably not what you want. For more information, see the documentation . If you want

Simply why does String.prototype log the string object with the standard curly brackets and key value pairs, and the Array.prototype log the array object just like an array, with square brackets and values? String.prototype.test = function(){ console.log(this); // logs { '0': 't', '1': 'e', '2': 's', '3': 't' } }; var str = 'test'; str.test(); Array.prototype.test1 = function(){ console.log(this); // [1,2,3,4] }; var arr = [1,2,3,4]; arr.test1(); Because in a method call the this argument is always (in sloppy mode) casted to an object. What you see is a String object, which was produced from

Lines 1-2 and 4-5 make sense in terms of the this returned. What am I missing about line 3? I thought it would return window similar to lines 4-5. Is there another pattern not in these 5 that could help demonstrate why? foo = { bar : function () { return this } } foo.bar() // ==> foo (foo.bar)() // ==> foo / but why? (foo.bar ? foo.bar : $.noop)() // ==> window (foo.bar || 0)() // ==> window The grouping operator does not destroy property references, which are provoking the method call. This is explicitly mentioned in the spec : NOTE: This algorithm does not apply GetValue to the result of