Check if a rectangle contains other one

JavaScript version
// Returns true if `a` contains `b`
// (x1, y1) and (x2, y2) are top-left and bottom-right corners
const contains = (a, b) => a.x1 <= b.x1 && a.y1 <= b.y1 && a.x2 >= b.x2 && a.y2 >= b.y2;
TypeScript version
interface Rect {
x1: number;
x2: number;
y1: number;
y2: number;
}
const contains = (a: Rect, b: Rect): boolean => a.x1 <= b.x1 && a.y1 <= b.y1 && a.x2 >= b.x2 && a.y2 >= b.y2;