this

I need help understanding $(this). Is it possible to narrow the focus of 'this' within the parentheses or does "this" preclude the use of any other attributes? For example: I don't understand why this code: $(this).children("div") can't be rewritten like this: $(this +" div") without having to resort to something like: $('#'+$(this).attr("id")+" div") Also, can you point me to 'this' in the JQuery documentation? It is difficult to use 'this' as a search term for obvious reasons. this isn't a jQuery "thing", but a basic JavaScript one . It can't be re-written the way you have in examples

I've come across a head scratching issue with my JavaScript application. If I write an element like this: <li onClick="alert(this.tagName)"></li> I get "LI." However if I do this: <li onClick="foo()"></li> Where "foo()" is: function foo(){ alert(this.tagName); } I get "undefined." I am away how "this" is supposed to work in regards to attached functions. But, I am baffled because "this" is not picking up the element, but apparently defaulting to "window." I can't figure out why this is happening. Does anyone have an explanation? That's because you aren't passing a reference to this in the

For example Intent intent = new Intent(this, SecondActivity.class); eclipse error: The method setClass(Context, Class) in the type Intent is not applicable for the arguments (FirstActivity.ClickEvent, Class) Intent intent = new Intent(FirstActivity.this, SecondActivity.class); But that will be correct. Anybody can explain the difference between those two ? Thanks. this refers to your current object. In your case you must have implemented the intent in an inner class ClickEvent, and thats what it points to. Activity.this points to the instance of the Activity you are currently in. When you are

I've just seen a weird behaviour of the this keyword in NodeJS environment. I'm listing them with code. I've run this codes with NodeJS v6.x , with a single JavaScript file. While testing with one line of code as follows, whether with or without the 'use strict' statement, this points to an empty object {} . console.log(this) But, when I'm running the statement within a self executing function like, (function(){ console.log(this); }()); It's printing a really big object. Seems to me the Global execution context object created by NodeJS environment. And while executing the above function with a

I have two classes with a parent-child relationship (the Parent class "has-a" Child class), and the Child class has a pointer back to the Parent . It would be nice to initialize the parent pointer upon construction of the child, as follows: class Child; class Parent; class Child { public: Child (Parent* parent_ptr_) : parent_ptr(parent_ptr_) {}; private: Parent* parent_ptr; }; class Parent { public: Parent() : child(this) {}; private: Child child; } Now, I know people recommend not using this in initialization list, and C++ FAQ says I'm gonna get a compiler warning (BTW, on VS2010, I don't get

This question already has an answer here: Self-references in object literals / initializers 23 answers I'm trying to calculate a proportional height (while excluding a static height element) from a width that gets passed in via a request (defaults to 560). However, wF.h evaluates to NaN . If I replace this.w with 560 it works, but not when trying to reference the w property of wF . var wF = { w : 560, h : (312 - 42) / (560 / this.w) + 42 }; What gives? I refuse to use two plain vars in succession, because I'm trying to get nice code out of JS. Update: Thanks to everyone who helped explain and

I'm interested what's the reason to have call() method in JS. It seems it duplicates usual method of calling this . For example, I have a code with call(). var obj = { objType: "Dog" } f = function(did_what, what) { alert(this.objType + " " + did_what + " " + what); } f.call(obj, "ate", "food"); The output is "Dog ate food". But the same result I can get assigning the function to the object. var obj = { objType: "Dog" } f = function(did_what, what) { alert(this.objType + " " + did_what + " " + what); } obj.a = f; obj.a("ate", "food"); The result is the same. But this way is more understandable