scope

问题 Can anyone explain why the following produces 1,2 and the other produces 5? Should they not both produce 5? //produces 1,2 (function () { var a = [5]; function bar() { if (!a) { var a = [1, 2]; } console.log(a.join()); } bar(); })(); Based on reading some articles about JS closure, I expect them both to produce 5. Can't seem to find an article anywhere that would give some insight as to why the first block produces otherwise. //produces 5 (function () { var a = [5]; function bar() { if (a) {

问题 I am trying to call one of my object's methods from within an array_map anonymous function. So far I am receiving the expected error of: Fatal error: Using $this when not in object context in... I know why I am getting this error, I just don't know a way to achieve what I am trying to... Does anybody have any suggestions? Here is my current code: // Loop through the data and ensure the numbers are formatted correctly array_map(function($value){ return $this->some_method($value,'value',false);

问题 I was wondering how javascript hoisting works for global variable. Let's say I have following code snippet: var a = 5; function print(){ console.warn("a",a,b); var a = 10; b=5; console.warn("a",a); } print(); In this case I am getting error "b is not defined". I wonder why Javascript hoisting is not working for global variable. I tried to look for this but getting results only for variable hoisting. Any thoughts?? 回答1: var statements are hoisted. function declarations are hoisted. Assignments

问题 Is it possible to access an inner variable from an external function like this example? function a(f) { var c = 'test'; f(); } a(function() { alert(c); //at this point, c should = "test" }); 回答1: No, that won't work. What matters is where (lexically) a function is defined , not where it's invoked. When figuring out what (if anything) "c" refers to, the language looks in the local scope, then in the next scope out based on the definition of the function . Thus if that invocation of "a" took

问题 This question is a furtherance of the one asked in this thread. Using the following class definitions: template <class T> class Foo { public: Foo (const foo_arg_t foo_arg) : _foo_arg(foo_arg) { /* do something for foo */ } T Foo_T; // either a TypeA or a TypeB - TBD foo_arg_t _foo_arg; }; template <class T> class Bar : public Foo<T> { public: Bar (const foo_arg_t bar_arg, const a_arg_t a_arg) : Foo<T>(bar_arg) // base-class initializer { Foo<T>::Foo_T = T(a_arg); } Bar (const foo_arg_t bar

问题 I have a function in one of my views, and I want to access one of the variables available to the view through CodeIgniter's data array. For example; in my controller I have this: $this->load->view('someview', array( 'info' => 'some info' )); Now, within my view, I have a function, and I want to be able to access the variable $info from within that function scope. Is that possible? 回答1: in your controller: $GLOBALS['var_available_in_function'] = $value; Your function: function get_var() {

问题 Earlier i saw this: .InstancePerApiRequest(); Now i only got this: .InstancePerHttpRequest(); Did autofac removed the API-scope? I have the reference Autofac.Integration.WebApi but this extension is not available. What is the difference between InstancePerHttpRequest and InstancePerApiRequest? 回答1: InstancePerApiRequest is part of the Web API integration, and InstancePerHttpRequest is part of the MVC integration. These both actually apply the same tag to the lifetime scope. That was done

问题 Say I have a file 'test.js' with the following contents: var test = 'something'; Then I have a primary script that needs to load up test.js to grab the test variable. Obviously this works: $.ajax({dataType: "script", cache: true, url: 'test.js'}); The issue is that the variable test exists in the global scope. I'm curious if there's a way to add it into an object and keep it out of the global scope. Something like: function scriptloader() { this.grabscript = function() { return $.ajax(

问题 Several of my functions require the UniversalXPConnect privilege to be enabled. netscape.security.PrivilegeManager.enablePrivilege('UniversalXPConnect'); So, my functions look like this: function oneOfMyFunctions() { netscape.security.PrivilegeManager.enablePrivilege('UniversalXPConnect'); // ... } Actually, I also try to catch the exception when the privilege is denied. Looks as follows: try { netscape.security.PrivilegeManager.enablePrivilege('UniversalXPConnect'); // ... } catch (e) { // .

问题 I have been reading the Garbage Collection chapter from Jeffrey Richter's fine book, "CLR via C#". There, he illustrated an example of how the GC conceptually works (how roots are marked) by referring to a disassembly listing of native code emitted from the JIT compiler. From that example, it occurred to me that nesting reference types in scope seems to have ZERO effect on expediting the garbage collection of the nested variable. I wonder if I am understanding this correctly. In any case,