1. if(map[‘key’])
let test = {name : 'lei'}
if(test["name"]){
console.log('success')
}else{
console.log('error')
}
2. in 运算符
let test = {name : 'lei'}
if('name' in test){
console.log('success')
}else{
console.log('error')
}
3.hasOwnProperty()
let test = {name : 'lei'}
if(test.hasOwnProperty('name')){
console.log('success')
}else{
console.log('error')
}