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Scope Ruby does not have the characteristics of a nested scope (that is, an internal scope that can see an external scope), its scope is completely separate, and once you enter a new scope, the original binding is replaced with a

Js scopes are used in a variety of ways and different results are produced in a single detail. Next I will summarize some instructions on js scopes. If you need them, please refer to them. This is an interview question to introduce the js scope in detail. The Code is as follows: Copy code Function foo (){Foo. abc = function () {alert ('alibaba ')}This. abc = function () {alert ('alimama ')}Abc = function () {alert ('alipay ')};

Scope chainIf you want to learn JavaScript well, there are three places that must be carefully mastered: two chains, one pack.Two chains: Scope Chain and prototype chainOne pack: Closures in JavaScript1. ScopeThere is no block-level scope in JavaScript, and scope partitioning is accomplished through function functions.

First look at an example: var name = ' laruence '; function echo() { Alert(name); var name = ' Eve '; Alert(name); Alert(age); } Echo(); What is the result of the operation?The above question, I believe there will be a lot of people will think is: Laruence Eve [Script ERROR] The second alert is ' Eve ' because it will be assumed that in Echo, the first alert will take the value of the global variable name and the second value is overwritte

Scope and scope chain:Reference article: http://www.cnblogs.com/malinlin/p/6028842.htmlHttp://www.cnblogs.com/lhb25/archive/2011/09/06/javascript-scope-chain.htmlhttp://www.zhangyunling.com/?p=134Summarize:①js are objects everywhere.An execution environment and variable object are created when the ② function executes③ code runs in the execution environment variab

environment is used, indicates the concrete existence of the environment. 3. What is a scope chain? (Scope chain) 　　When the code is executed in an environment, a scope chain consisting of variable objects is created.. The purpose of the scope chain is to ensure that all variables and functions that are accessible to

Before you beginBecause I am also a JavaScript beginner, record learning pass, afraid later will forget.For JavaScript beginners, the hardest part is not the Code section, but the understanding of the terminology in many books, and most of the time you want to understand what is explained in a JavaScript book, it involves a lot of terminology, In the absence of the terminology will be the content of the understanding of the deviation (resulting in difficult to remember the content of the study),

1. Scope and scope chainIn JavaScript, a function is also an object. For a function, each context object that can be accessed by the function is called the scope of the function. All properties and methods in the scope can be accessed by the function. In the following code, the scopes of functions F1 and F2 are global

First, the prototype chain (family genealogy) Concept: JS inside the object may have a parent object, the parent object will also have a parent object, ... Ancestors Root: Inherit Property: There is almost always a __proto__ property in the object that points to the meaning of his parent object: You can implement the object to access the related property in the parent object Root object: Object.prototype var arr=[1,3,5]arr.__proto__:array.prototypea

JavaScript uses lexicalscoping. The scope of variables that function execution depends on is determined by the function definition, rather than the function execution, this article introduces the knowledge of JavaScript scope chain, execution context, and closure. If you are interested, learning about closure and scope chain is an important concept in JavaScript,

JavaScript variable Scope detailed The scope of a variable is the region in the program that defines the variable. The scope of a variable is also called a scope, which refers to the valid range of a variable in the program. Depending on the scope, variables can be divided

Python variable ScopeVariable Scope LEGB1. Scope of variablesWhen you create, change, or find a variable name in a Python program, it is done in a space (namespace) that holds the variable name, which we call the scope. The scope of the Python is static, where the variable name is assigned in the source code to determi

a summary of the basic functions of JS including lexical scope and module Foundation. 1 Compiler---scope---engineThe compiler is responsible for parsing and code generation, and the scope is responsible for maintaining a series of queries that consist of all identifiers (variables), and the engine is responsible for executing the code according to the rules defin

Nested functions (Scope chain) When you are nesting a function, be aware that the actual scope chain is changing, which may not seem intuitive. You can put the following code into the Firebug monitoring value changes. Copy Code code as follows: var testvar = ' Window property '; var O1 = {testvar: ' 1 ', fun:function () {alert (' O1: ' +this.testvar+ ' var O2 = {testvar: ' 2 ', fun:functio

Copy Code code as follows: /* Code 1 * * var scope = "global"; function Checkscope () { var scope = "local"; function Childcheck () { var scope = "Childlocal"; document.write (scope); } function childundefined () { document.write (scope); var

Source: http://www.laruence.com/2009/05/28/863.html Question proposal First, let's look at an example:VaR name = 'laruence ';Function echo (){Alert (name );VaR name = 'Eve ';Alert (name );Alert (AGE );}Echo (); What is the running result? I believe many people will think of the problem as follows:LaruenceEve[Script Error] In ECHO, the value of the global variable name is obtained during the first alert operation, and the second value is overwritten by the local variable name. Therefore, the seco

Before the scope of the chain in my eyes is just the call to an object layer up to find their own required variables or functions, if not the return undefined, in fact, it is generally said, but I need to be constantly in-depth.Remember two words before you dive into your understandingAll objects in 1.js, functions are objects2. Functions run within the scope they are defined in, not in the

The following variables have global scope: 1. All definitions in the outermost variable (non-function body part) have global scope. 2. A variable that does not define a direct assignment is declared as a global scope. 3. Properties of all window objects have global scope. The following variables have function scope

The scope and context (contexts) in JavaScript are unique to the language, thanks in part to the flexibility they bring. Each function has a different context and scope of variables. These concepts are backed by some powerful design patterns in JavaScript. However, this also brings a lot of confusion to the developers. The following is a complete revelation of the context and

the memory, and then point to this region through a fn2 variable. The function in this region is not named at first, this type of function is called an anonymous function or lambda function. If we call fn2 () before creating a function, the program reports an error. Function scope chain In JavaScript, when a function is called, an execution environment is created, and an attribute SCOPE is added for each f