Angular 4 MEAN 堆栈获取可观察的长度

Question

I use a service function in my Angular 4 app to retrieve data from the MongoDB/Express.js backend:

getArticles() {
  return this.http.get('api/articles').map(res => res.json());
}

How do I get the length of the received array?

Update:

I should have clarified, I needed to find a length of an Observable array.

Answer 1

var size = Object.keys(myObj).length; . Object.keys() 'returns an array of a given object's own enumerable properties', from MDN . So if you do Object.keys(myObj) you will get an array of enumerable properties. Doing .length on that array will provide you with the number of enumerable properties.

Answer 2

Found the solution here: https://stackoverflow.com/a/40237063/5861479 In my case it would be something like this:

getArticlesLength() {
  return this.http.get('api/articles')
    .map(res => res.json()).subscribe(result => {console.log(result.length)});
}