JS代码，从一个数组中得到连号的数并显示

JavaScript code

function m() {
            var k = [1, 2, 7, 8, 9, 11, 22, 35, 36];
            if (k.length == 0)
                return;
            var first = 0;
            var old = 0;
            var now = 0;
            for (var i = 0; i < k.length; i++) {
                if (i == 0) {
                    first = k[i];
                    old = k[i];
                    now = k[i];
                } else {
                    now = k[i];
                    if (now == old + 1) {
                        old = now;
                        if (i == k.length - 1) {
                            if (old != first) {
                                document.write("连号: 从" + first + "到" + old + "<br>");
                            }
                        }
                        continue;
                    } else {
                        if (old != first) {
                            document.write("连号: 从" + first + "到" + old + "<br>");
                        }
                        first = k[i];
                        old = k[i];
                        now = k[i];
                    }
                }
            }
        }
//输出
//连号: 从1到2
//连号: 从7到9
//连号: 从35到36