Object’s function:

Definition of an object: What is an object and is an object a complex data type

The object is used to store multiple data as key-value pairs

Similarities and differences between objects and arrays

(1) Similarities: Both are complex data types and can store multiple data

(2) Differences: Different storage methods

  • Array: Ordered storage

  • Object: Unordered storage (key-value pairs)

Object syntax

A statement object

Let object name = {attribute name: attribute value, attribute name: attribute value,}Copy the code

Object value

Syntax: object name. attribute name

Features:

  • Object name [‘ Property name ‘] resolves to property name if there is a string inside []

  • Object name [variable name] If there is no string inside [], it is resolved to the variable name

Details: What data type is an attribute value in an object that can be retrieved using all the syntax of that type

  • Object whose property value is an array can be: object name. Attribute name [subscript]

  • If the attribute value of an object is a function, it can be: object name. The attribute name ()

Object assignment

Syntax: (1) Object name. Attribute name = value (2) Object name [‘ attribute name ‘] = value

Attributes :(1) if the attribute name exists, it means’ modify ‘the attribute value. (2) if the attribute name does not exist, it means’ add’ the attribute

(3) Delete object attributes :delete object name. The property name

Object traversal

Syntax: for(let key in object name){object name [key]}

 let obj = {
        name: 'summer'.age: 18.sex: 'woman'.hobby:'learning'
      }

      for( let key in obj){
        // Consider: key is a variable. What syntax should be used to fetch the value of an object's attribute
          console.log( key )//'name' 'age' 'sex' 'hobby'
        // console.log( obj[ 'key' ] )//undefined
        // console.log( obj.key )//undefined
          console.log( obj[ key ] )//'summer' 18 'nv'
      }
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