由于 JavaScript 是个单线程模型的编程语言，因此任一时刻，正在运行的执行上下文只能有一个，称为 active EC；其他的 EC 则依它们被调用的先后次序，形成了一个后入先出的栈结构，简称 EC Stack。最地下的 EC 通常是 Global EC。EC 的创建与闭包实现的关键：作用域链 Scope Chain 每个函数执行时，都会生成一个 EC
Lexical scoping is a set of rules for how and where the engine looks for variables. The most important feature of lexical scope is that itsdefinition process occurs in the writing phase of the code(assuming you do not use eval or with), that is, your scope is determined after you write ...
Scope is formed of a linked nesting of lexical environments, with each level in the nesting corresponding to a lexical environment of an ancestor execution context. These linked lexical environments form a scope "chain". Identifier resolution is the process of searching along this chain for a matc...
Scopes and closures are important in JavaScript. But, they were confusing for me when I first started. Here’s an explanation of scopes and closures to help you understand what they are. Let’s start with scopes. Scope A scope in JavaScript defines what variables you have access to. There ...
Scope chain refers to the fact that parent scope does not have access to the variables inside its children's scope, but thechildren's scope does have access to the variables present in its parent scopes. 标识符查找:JS查找变量最先查找当前作用域,如果在当前作用域没找到变量的声明,会向外层嵌套的...