• 取值
  用object.prop方式取值

var company = {
    name: 'google',
    age: '28',
    money: 'I do not known'
}
company.name            //'google'

• 用object['propname']
  當屬性名不是一個有效的變量名時，只能使用這種方法獲取

var company = {
    name: 'google',
    age: '28',
    money: 'I do not known',
    'my-job': 'coding'
}
company['my-job']       // 'coding'

注意：定義一個Object時，屬性名盡量為有效的變量名，這樣便于取值

• 可以自由的添加刪除對象的屬性

var jake = {
    name: '小明'
};
jake.age; // undefined
jake.age = 18; // 新增一個age屬性
jake.age; // 18
delete jake.age; // 刪除age屬性
jake.age; // undefined
delete jake['name']; // 刪除name屬性
jake.name; // undefined
delete jake.school; // 刪除一個不存在的school屬性也不會報錯

判斷Object的某個屬性是否存在

• in

var company = {
    name: 'google',
    age: '28',
    money: 'I do not known'
}
'name' in company       // true
'age' in company       // true

• hasOwnProperty

var company = {...}
'name' in company       // true
'toString' in company   // true 

in雖然能判斷屬性是否存在，但是對象繼承的屬性也會參與判斷，就導致上面這種情況，這時就需要使用hasOwnProperty

var company = {...}
company.hasOwnProperty('name')       // true
company.hasOwnProperty('toString')   // false