ECMA-262-5

There are 6 posts tagged ECMA-262-5.

ECMA-262-5 in detail. Chapter 3.2. Lexical environments: ECMAScript implementation.

Read this article in Chinese.

  1. Introduction
  2. Definitions
  3. Environment record types
    1. Declarative environment record
      1. Eval and inner functions may break optimizations
    2. Object environment record
  4. Structure of execution context
    1. This binding
    2. Variable environment
    3. Lexical environment
  5. Identifier resolution
  6. Conclusion
  7. Additional literature

Introduction

In this chapter we continue our consideration of lexical environments. In the previous sub chapter 3.1 we clarified the general theory related with the topic. In particular we have learned that the concept of environments is closely related with concepts of static scope and closures. Continue reading →

ECMA-262-5 in detail. Chapter 3.1. Lexical environments: Common Theory.

  1. Introduction
  2. Common Theory
    1. Scope
      1. Static (lexical) scope
      2. Dynamic scope
        1. With and eval as dynamic scope features in ECMAScript
    2. Name binding
      1. Rebinding
      2. Mutation
    3. Environment
      1. Activation record model
      2. Environment frames model
        1. First-class functions
        2. Funargs and higher-order functions
        3. Free variable
        4. Environment definition
        5. Rules of function creation and application
        6. Closure
        7. Funarg problem
      3. Combined environment frame model
  3. Conclusion
  4. Additional literature

Introduction

In this chapter we’ll talk in detail about lexical environments — a mechanism used in some languages to manage the static scoping. In order to understand this concept completely, we’ll also discuss briefly the alternative — dynamic scoping (which though isn’t used directly in ECMAScript). We’ll see how environments help to manage lexically nested structures of a code and to provide complete support of closures. Continue reading →

ECMA-262-5 in detail. Chapter 2. Strict Mode.

  1. Introduction
  2. Strict mode features
    1. Reasons
    2. Definition
    3. Strictness scope
  3. Strict mode restrictions
    1. Future reserved keywords
    2. Octal extension for literals
    3. Assignment to an undeclared identifier
    4. Assignment to read-only properties
      1. Shadowing inherited read-only properties
    5. Creating a new property of non-extensible objects
    6. eval and arguments restrictions
    7. callee and caller restrictions
    8. Duplications
    9. delete operator restrictions
    10. with statement
    11. this value restrictions
      1. Indirect eval call
  4. Conclusion
  5. Additional literature

Introduction

In this chapter we will concentrate on another feature of the ECMA-262-5. The topic of the discussion is a strict variant (or strict mode) of an ECMAScript program. We’ll discuss the reasons for providing this feature, how it affects on some already existing semantic aspects and what can it restrict. Continue reading →

ECMA-262-5 in detail. Chapter 1. Properties and Property Descriptors.

Read this article in: Russian.

  1. Introduction
  2. New API methods
  3. Property kinds
    1. Property attributes
    2. Named data property
    3. Named accessor property
    4. Internal property
  4. Property Descriptor and Property Identifier types
  5. Conclusion
  6. Additional literature

Introduction

This chapter is devoted generally to one of new concepts of the ECMA-262-5 specification — to property attributes and mechanism of their handling — property descriptors.

Usually saying that “an object has some property” we mean an association between a property name and its value. But as we know from the ES3 analysis, a property structure is more complex than just a string name. It also has set of attributes — those which we already discussed in ES3, e.g. {ReadOnly}, {DontEnum} and other. So from this viewpoint a property is as an object itself. Continue reading →

Тонкости ECMA-262-5. Часть 1. Свойства и дескрипторы свойств

Read this article in: English.

  1. Введение
  2. Новые методы API
  3. Виды Свойств
    1. Атрибуты свойств
    2. Именованные свойства-данные
    3. Именованные аксессор-свойства
    4. Внутренние свойства
  4. Дескриптор свойств и типы идентификаторов свойств
  5. Заключение
  6. Дополнительная литература

Введение

Эта глава посвященна одной из новых концепций в спецификации ECMA-262-5 — атрибутам свойств и механизму работы с ними, дескрипторам свойств.

Обычно, говоря, что объект имеет какие-то свойства, мы имеем ввиду связь между именем свойства и его значением. Но, как мы знаем из анализа ES3, структура свойства несколько сложнее, чем просто строковое имя. Оно также имеет набор атрибутов — те, которые мы уже обсудили в статьях об ES3, например {ReadOnly}, {DontEnum} и другие. С этой точки зрения свойство само по себе является объектом. Continue reading →

ECMA-262-5 in detail. Chapter 0. Introduction.

We have finished analysis of the most important parts and theoretical aspects concerning 3rd edition of the ECMA-262 specification, i.e. standard devoted ECMAScript programming language. We have done and achieved a lot. Originally written in Russian, this series after more than half an year has been translated to several languages, what allowed this information to be shared with JavaScript developers and with everyone who interested in deep ECMAScript allover the world. Continue reading →