var a;

with (Math) a = PI;

var b = {
  get_member: function () {
    return this.member;
  },
  member: 41
};

with (b) {
  let a = get_member(); //<--- a is local for this block
  var c = a + 1;
}

result = a == Math.PI && c == 42;
console.log(result);