JSFiddle - React, Tailwind, and code Playground

HTML

<input type="hidden" value="12:34:00" name="timetemp0" />
<input type="hidden" value="14:45:00" name="timetemp1" />
<input type="hidden" value="15:12:00" name="timetemp2" />
<input type="hidden" value="16:42:12" name="timetemp3" />
<input type="hidden" value="16:54:56" name="timetemp4" />
<input type="hidden" value="" name="timetemp5" />
<input type="button" value="Test" onclick="CheckHiddenInputs()" />

JavaScript

var timeTempCount = 5;

for (var i = 0; i <= timeTempCount; i++) {
    var timeTemp = document.getElementsByName('timetemp' + i);

    if (timeTemp[0].value == '') {
        alert('No value');
    }
    else {
        alert(timeTemp[0].value);
    }
}