Data typeBefore introducing symbol, let's briefly describe the JavaScript data type:JavaScript has 6 data types, namely:
string literal type
Number numeric type
Object type
Boolean Boolean value type
Null empty value
JavaScript Symbol type
Depending on the specification, the object property key can only be string or symbol type, not number, Boolean, only string and symbol two types.We typically compare attribute string, and now look at the advantages that the
ES5 object property names are strings, which can easily cause property names to conflict. For example, if you use an object provided by another person but want to add a new method to the object (mixin mode), the name of the new method may conflict
In Javascript ES6, the use of the data type Symbol is described in detail.
Introduction
Symbol is a special and unchangeable data type. It can be used as an identifier of an object property to indicate unique values. The Symbol object is an implicit
SymbolOverview as symbol instance of property name: Eliminates the traversal of the Magic string property name Symbol.for (), Symbol.keyfor () instance: the Symbol value built into the module's Singleton mode
Overview
ES5 object property names are
What is Symbol?
Symbols is not an icon, nor does it mean that you can use a small picture in your code:
Nor does it refer to the grammar of other things. So, what exactly is Symbol to?Seven types of data
When JavaScript was normalized in 1997,
Symbol resolves property name conflicts for objects
Remember some of the data types we know.
String number Object undefined Null
Boolean
Now, one more type is symbol.
Let A=symbol ()
Console.log (a)//symbol ()
Console.log (typeof a)//symbol
The code
Discussion on the technology of symbol mc1000 ----- the code of the display. Reg light-on under Platform
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Javascript has two ways of determining whether two values are equal.
Equality symbol
The equality symbol consists of two equals: = =Javascript is a weakly typed language. This means that the equality symbol will cast the type in order to compare
The ES5 object property name is a string that can easily cause a violation of property names.Eg:var a = {name: ' lucy '};a.name = ' Lili ';This will override the propertyES6 introduces a new primitive data type, symbol, that represents a unique
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