The subject asks me to determine if she has this attribute? three ways

pro in obj is enough;

This method can determine whether the object's own properties and inherited properties exist.

Properties in object:

    let infoObj = {
    
    
      name: "六卿",
      age: 18,
      habby: ['唱歌', '贪财好色'],
      friends: {
    
    
        '张三': 'Y',
        '小李': 'N'
      }
    }
    console.log('name' in infoObj, 'name')
    console.log('age' in infoObj, 'age')
    console.log('habby' in infoObj, 'habby')
    console.log('friends' in infoObj, 'friends')
    console.log('六卿' in infoObj, '六卿')
    console.log('张三' in infoObj.friends, '张三')
    console.log('小李' in infoObj.friends, '小李')
    console.log('六卿' in infoObj.friends, '六卿')

You can also use the hasOwnProperty() method that comes with the object to judge
. Usage: object.hasOwnProperty(pro) returns a boolean value
Note: Only the senior attributes of the object can be judged, and the inherited attributes cannot be judged

You can also use or directly use if judgment or trinocular judgment