merge two object arrays with Angular 2 and TypeScript?

The spread operator is kinda cool.

this.results = [ ...this.results, ...data.results];

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The spread operator allows you to easily place an expanded version of an array into another array.

You can read about spread operator here.

I think that you should use rather the following:

data => {
  this.results = this.results.concat(data.results);
  this._next = data.next;
},

From the concat doc:

The concat() method returns a new array comprised of the array on which it is called joined with the array(s) and/or value(s) provided as arguments.

With angular 6 spread operator and concat not work. You can resolve it easy:

result.push(...data);