1. Declare two syntax for objects

let obj = { 'name':'frank','age': 18 }
let obj = new Object({'name': 'frank'})
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2. How do I delete object attributes

delete obj.xxx 
delete obj['xxx']
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Contains no attribute name

'xxx' in obj.xxx === undefined
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Contains the attribute name, but the value is undefined

'xxx' in obj && obj.xxx === undefined

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3. View object properties

• View all of its properties

Object.keys(obj)
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• View self + Common properties

console.dir(obj)

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Or print obj.proto in sequence with Object.keys

• A property is judged to be self – owned or common

obj.hasOwnProperty("xxx")
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4. How do I modify or add attributes of an object

• Direct assignment

Obj ['name'] ='frank' obj['na'+'me']='frank' obj['na'+'me']='frank'Copy the code

• Batch assignment

Object.assign(obj, {age: 18, gender:'man'})
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5. How do I modify or add attributes of an object

• Common attributes cannot be modified or added by themselves

Let obj ={},obj2={} // toString obj. ToString = 'XXX' will only change obj's own property obj2. ToString is still on the prototypeCopy the code

• Hard modify or add attributes to the prototype

Obj. __proto__. ToString = 'XXX' / / do not recommend the application Object. The prototype. ToString = 'XXX'Copy the code

In general, don’t modify a prototype, it can cause a lot of problems

• Modifying hidden attributes

let obj = {name: 'frank'}
let common = {kind:'human'}
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• Object. Create is recommended

let obj = Object.create(common)
obj.name = 'frank'
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6. ‘name’ in obj and obj.hasOwnProperty(‘name’

Object obj contains its own attribute ‘name’