ranges

const range = (sh, sm = 0, eh = 0, em = 0) => ({
  start: (sh * 100) + sm,
  end: (eh * 100) + em
});

// const A = [ range(9, 0, 10, 0) ];
// const B = [ range(9, 0, 9, 30) ];

// const A = [ range(9, 0, 10, 0) ];
// const B = [ range(9, 15, 9, 30) ];

// const A = [ range(9, 0, 10, 0) ];
// const B = [ range(9, 0, 10, 0) ];

// const A = [ range(9, 0, 9, 30) ];
// const B = [ range(9, 30, 15) ];

// const A = [ range(9, 0, 9, 30), range(10, 0, 10, 30) ];
// const B = [ range(9, 15, 10, 15) ];

const A = [ range(9, 0, 11, 0), range(13, 0, 15, 0) ];
const B = [ range(9, 0, 9, 15), range(10, 0, 10, 15), range(12, 30, 16, 0) ];

// console.log(A);
// console.log(B);

// for each time range...
for (var i = 0; i < B.length; i++) {
  var time = B[i];

  for (var j = 0; j < A.length; j++) {

    // case 1 - delete a block with the same start times
    // if the end time is in this range, the start is now the end
    // else delete this block (its all bad)
    if (time.start === A[j].start) {
      if (time.end < A[j].end) {
        A[j].start = time.end;
      } else { 
        A.splice(j, 1);
      }
    }

    // case  2 - delete times that fall inside of a block
    else if (time.start >= A[j].start && time.start <= A[j].end) {

      // this start time is in this block, and ends past this block
      // so we delete the rest of the block
      if (time.end >= A[j].end) {
        A[j].end = time.start;
      }
      // the end time falls in this block, so we have to splice
      // this block into two different ones (taking 15mins out of an hour)
      else {
        // update this one first
        var tempEnd = A[j].end;
        A[j].end = time.start;
        // add a new one
        A.splice(j + 1, 0, { start: time.end, end: tempEnd });
      }

    }

    else if (time.start >= A[j].start && time.end <= A[j].end) {
      A[j].start = time.end;
    }

    // delete the whole block
    else if (time.start <= A[j].start && time.end >= A[j].end) {
      A.splice(j, 1);
    }

  }

}

console.log(A);