[рони]

dc65k,

<script>
/*
input:
    [
        [9, 10],
        [15, 17],
        [14, 16],
    ]
output:
    [
        [10, 14],
        [17, 18],
    ]
*/
const input = [
        [9, 10],
        [15, 17],
        [14, 16]
        ];
const getWorkTime = (input, min, max) => {
    let ar = [], temp = [], push;
    for (let i = min; i <= max; i++) {
        let clear = input.some(([a, b]) => i >= a && i < b);
        let len = temp.length;
        if (clear) {
            if (len) {
                temp[1] = i;
                temp = [];
                push = false;
            }
        } else temp[+!!len] = i;
        if (temp.length == 2 && !push) {
        ar.push(temp);
        push = true;
        }
    }
    return ar
}
let a = getWorkTime(input, 9, 18);
document.write(JSON.stringify(a))
    </script>