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JavaScript built-in objects mainly refer to some global value properties, functions and constructor objects used to instantiate other objects that exist in the global scope before the program execution.

This article operating environment: windows7 system, javascript1.8.5 version, Dell G3 computer.

What is a JavaScript built-in object?

Js built-in objects:

The built-in objects in js mainly refer to some global value properties, functions and construction function objects defined by js that exist in the global scope before the program execution. Generally, we often use global variable values such as NaN, undefined, global functions such as parseInt (), parseFloat () to instantiate object constructors such as Date, Object, and so on, as well as single built-in objects such as Math objects that provide mathematical calculation.

Knowledge points involved:

Global objects (global objects), or standard built-in objects, should not be confused with "global objects (global object)". The overall object here is to say that in

Objects in the global scope. Other objects in the global scope can be created by the user's script or provided by the host program.

Classification of standard built-in objects

(1) value attributes, which return a simple value that does not have its own properties and methods.

For example, Infinity, NaN, undefined, null literals

(2) function attribute. The global function can be called directly. There is no need to specify the object when the function is called. After execution, the result will be returned directly to the caller.

For example, eval (), parseFloat (), parseInt (), etc.

(3) basic objects, which are the basis for defining or using other objects. Basic objects include general objects, function objects, and error objects.

For example, Object, Function, Boolean, Symbol, Error, etc.

(4) number and date objects, used to represent numbers, dates, and objects that perform mathematical calculations.

For example, Number, Math, Date

(5) string, an object used to represent and manipulate a string.

For example, String, RegExp

(6) indexable collection objects that represent data collections sorted by index values, including arrays and type arrays, as well as objects with class array structures. For example, Array

(7) Collection objects using keys, which use keys when storing data and support iterating elements in the order in which they are inserted.

For example, Map, Set, WeakMap, WeakSet

(8) Vector set, the data in the SIMD vector set will be organized into a data sequence.

Such as SIMD, etc.

(9) structured data, these objects are used to represent and manipulate structured buffer data, or data encoded by JSON.

Such as JSON, etc.

(10) Control abstract objects

For example, Promise, Generator, etc.

(11) reflection

For example, Reflect, Proxy

(12) internationalization, objects that are added to ECMAScript to support multilingual processing.

For example, Intl, Intl.Collator, etc.

(13) WebAssembly

(14) other

For example, arguments

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