Angular 2+ / Typescript无法读取未定义的属性

Question

I am using Angular 7 and I am getting this data from a service:

{name: "peter", datetime: 1557996975991}

Then I have this method that gets the data:

myMethod() {

    this.myService.getdata().subscribe((res) => {

      console.log(res); // returns: {name: "peter", datetime: 1557996975991}

      console.log(res[0].datatime); // Gives Error: Cannot read property 'datetime' of undefined 

    }); 

}

When I try to get the datatime value I'm getting:

Gives Error: Cannot read property 'datetime' of undefined

How can I fix this?

Answer 1

The res variable is object not array.

You need change to console.log(res.datatime);

Change to

myMethod() {

    this.myService.getdata().subscribe((res: any) => {

      console.log(res); // returns: {name: "peter", datetime: 1557996975991}

      console.log(res.datatime);

    }); 

}

Answer 2

您从对象中获得价值使用此

console.log(res.datetime)

Answer 3

You are confusing your objects and arrays.

When you do console.log(res[0].datatime) , you're understanding the response as an array when you can clearly see it is an object here: {name: "peter", datetime: 1557996975991} .

As Hein pointed, you should access the datatime property with console.log(res.datatime)

Answer 4

console.log(res.datetime); - note the e in datetime .

Answer 5

Yes as @FailedUnitTest has said you the best way is declare an interface and in that way you can access to this values. Avoid use 'any' always because when the code gets harder and bigger maybe you could get into some troubles.