How to get DOM elements by class, id, selectors and properties

Question

How can I get DOM elements by class, id, selectors (div > .my-i) and properties like in jQuery?

For example:

Answer 1

constructor(private elRef:ElementRef) {}

ngAfterViewInit() {
  this.elRef.nativeElement.querySelector('.myClass');
}

This will not work well with Web Workers or Universal, but Angular2 itself doesn't provide something platform-agnostic to query for elements.

See also angular 2 / typescript : get hold of an element in the template