carroty,
<!DOCTYPE HTML>
<html>
<head>
<title>Untitled</title>
<meta charset="utf-8">
</head>
<body>
<form id="timetable_city" name="timetable_city" action="/admin/timetable/add-timetable-city" method="post">
<input type="hidden" name="timetable_id" value="" id="timetable_id">
<input type="checkbox" name="day_1_ukr" id="day_1_ukr" value="yes" data-rel="1">
<input type="checkbox" name="day_2_ukr" id="day_2_ukr" value="yes" data-rel="2">
<input type="checkbox" name="day_3_ukr" id="day_3_ukr" value="yes" data-rel="3">
<input type="checkbox" name="day_4_ukr" id="day_4_ukr" value="yes" data-rel="4">
<input type="checkbox" name="day_5_ukr" id="day_5_ukr" value="yes" data-rel="5">
<input type="checkbox" name="day_6_ukr" id="day_6_ukr" value="yes" data-rel="6">
<input type="checkbox" name="day_7_ukr" id="day_7_ukr" value="yes" data-rel="7"><br>
<input type="text" name="time_1_ukr" id="time_1_ukr" value="" data-rel="1">
<input type="text" name="time_2_ukr" id="time_2_ukr" value="" data-rel="2">
<input type="text" name="time_3_ukr" id="time_3_ukr" value="" data-rel="3">
<input type="text" name="time_4_ukr" id="time_4_ukr" value="" data-rel="4">
<input type="text" name="time_5_ukr" id="time_5_ukr" value="" data-rel="5">
<input type="text" name="time_6_ukr" id="time_6_ukr" value="" data-rel="6">
<input type="text" name="time_7_ukr" id="time_7_ukr" value="" data-rel="7">
</form>
<div class="switch_checkbox all_times1">
<input type="checkbox" class="all_time1" />
<label><i>Время</i></label>
</div>
<script>
var time = document.querySelector(".all_time1"),
times = document.querySelectorAll("[id^=time_]"),
days = document.querySelectorAll("[id^=day_]");
time.onclick = function () {
var b = "";
if (time.checked==!0) {
for (var a = 0; a < times.length; a++)
if (times[a].value) {
b = times[a].value;
break
}
for (a = 0; a < times.length; a++)!0 == days[a].checked && (times[a].value = b)
}
};
</script>
</body>
</html>