Overview of ES6 at 350 points. Part two

My series of notes ES6 in Depth , consisting of 24 entries, describes most of the syntax changes and innovations in ES6. In this publication, I will summarize everything stated in previous articles in order to give an opportunity to look again at everything together.



Content

• Introduction
• Tools
• Assignment Destructing
• Spread Operator and Rest Parameters
• Arrow functions
• Pattern lines
• Object Literals
• Classes
• Let and Const
• Characters
• Iterators
• Generators
• Promises
• Maps
• Weakmaps
• Sets
• Weaksets
• Proxy
• Reflection
• Number
• Math
• Array
• Object
• Strings and Unicode
• Modules

Part one: here.
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Characters

• New primitive data type in ES6.
• You can create your own symbols: var symbol = Symbol()
var symbol = Symbol()

• You can add descriptions for Symbol('ponyfoo')
debugging needs Symbol('ponyfoo')
Symbol('ponyfoo')

• Symbols are immutable and unique: Symbol()
Symbol()
, Symbol()
Symbol()
, Symbol('foo')
Symbol('foo')
and Symbol('foo')
Symbol('foo')
- all different.
• Type of symbols - symbol
symbol
so typeof Symbol() === 'symbol'
typeof Symbol() === 'symbol'
.
• You can create global symbols with Symbol.for(key)
Symbol.for(key)
.

• If the character with this key
key
exists, the call will return it.
• Otherwise a new character with key
will be created. key
as a description.
• Symbol.keyFor(symbol)
Is an inverse function that accepts symbol
symbol
and returning its key
key
.
• Global symbols are global, as far as possible, that is, absolutely. For access to symbols, a single global register is used:
• context window
window
;
• eval
context eval
;
• context .