响应的json方法的返回类型是什么？

Question

I see some examples of Angular 2, which convert the response of http into JavaScript object like this:

http.get("http://....").subscribe(
    response => {
        let result = response.json();
    },
    error => { 
        console.log('cannot get api');
    }
);

I also see some examples which state that json() method returns a Promise, which requires the function to be enclosed in then to obtain the result:

response.json().then(result => ({
    ///
});

Why does one use then and the other does not? What's the return of value of json and which should I use?

Answer 1

The examples where you see response.json() returning a Promise are part of the Fetch API, which is still experimental: https://developer.mozilla.org/en-US/docs/Web/API/Response

Body.json()

Takes a Response stream and reads it to completion. It returns a promise that resolves with a JSON object.

The other example you see are from Angular's implementation which returns the data directly instead of a Promise : https://github.com/angular/angular/blob/master/packages/http/src/body.ts#L26