Easily check if a number is in a given Range in Dart?

Quite simply, no. Just use 1 <= i && i <= 10.

Since the inclusion of extension functions, this answer could be changed slightly if you are okay with doing the checks non-inline.

To my knowledge, there is no built in functions for this, but you could easily create your own extension on num to simulate this.

Something like this would simulate a range verification:

void main() {
  final i = 2;
  if (i.isBetween(1, 10)) {
    print('Between');
  } else {
    print('Not between');
  }
}

extension Range on num {
  bool isBetween(num from, num to) {
    return from < this && this < to;
  }
}

This method in particular is exclusive both from and to, but with minor tweaking and better naming you could easily create extension functions for all of the Kotlin range checks.