index.js

function getElementById() {
  elements = new Array();
  for (var i = 0; i < arguments.length; i++) {
    var element = arguments[i];
    if (typeof element == "string") element = document.getElementById(element);
    if (arguments.length == 1) return element;
    elements.push(element);
  }
  return elements;
}
function hi() {
  document.getElementById("t1").style.display = "none";
  document.getElementById("t2").style.display = "none";
  document.getElementById("t3").style.display = "none";
  document.getElementById("t4").style.display = "none";
  document.getElementById("t5").style.display = "none";
  document.getElementById("t6").style.display = "none";
}
function uc1() {
  document.getElementById("t1").style.display = "block";
}
function uc2() {
  document.getElementById("t2").style.display = "block";
}
function uc3() {
  document.getElementById("t3").style.display = "block";
}
function uc4() {
  document.getElementById("t4").style.display = "block";
}
function uc5() {
  document.getElementById("t5").style.display = "block";
}
function uc6() {
  document.getElementById("t6").style.display = "block";
}
function len() {
  var from = document.getElementById("flength").value;
  var to = document.getElementById("tlength").value;
  var totext =
    document.getElementById("tlength").options[
      document.getElementById("tlength").selectedIndex
    ].text;
  var ip = document.getElementById("lip").value;
  if (
    document.getElementById("lip").value == null ||
    document.getElementById("lip").value.length == 0
  )
    document.getElementById("lop").value = "Please enter No. of Units";
  else
    document.getElementById("lop").value =
      Math.round(((ip * from) / to) * 100000) / 100000 + " " + totext;
}
function area() {
  var from = document.getElementById("farea").value;
  var to = document.getElementById("tarea").value;
  var totext =
    document.getElementById("tarea").options[
      document.getElementById("tarea").selectedIndex
    ].text;
  ip = document.getElementById("aip").value;
  if (
    document.getElementById("aip").value == null ||
    document.getElementById("aip").value.length == 0
  )
    document.getElementById("aop").value = "Please enter No. of Units";
  else
    document.getElementById("aop").value =
      Math.round(((ip * from) / to) * 100000) / 100000 + " " + totext;
}
function speed() {
  var from = document.getElementById("fspeed").value;
  var to = document.getElementById("tspeed").value;
  var totext =
    document.getElementById("tspeed").options[
      document.getElementById("tspeed").selectedIndex
    ].text;
  var ip = document.getElementById("sip").value;
  if (
    document.getElementById("sip").value == null ||
    document.getElementById("sip").value.length == 0
  )
    document.getElementById("sop").value = "Please enter No. of Units";
  else
    document.getElementById("sop").value =
      Math.round(((ip * from) / to) * 100000) / 100000 + " " + totext;
}
function weight() {
  var from = document.getElementById("fweight").value;
  var to = document.getElementById("tweight").value;
  var ip = document.getElementById("wip").value;
  var totext =
    document.getElementById("tweight").options[
      document.getElementById("tweight").selectedIndex
    ].text;
  if (
    document.getElementById("wip").value == null ||
    document.getElementById("wip").value.length == 0
  )
    document.getElementById("wop").value = "Please enter No. of Units";
  else
    document.getElementById("wop").value =
      Math.round(((ip * from) / to) * 100000) / 100000 + " " + totext;
}
function vol() {
  var from = document.getElementById("fvol").value;
  var to = document.getElementById("tvol").value;
  var ip = document.getElementById("vip").value;
  var totext =
    document.getElementById("tvol").options[
      document.getElementById("tvol").selectedIndex
    ].text;
  if (
    document.getElementById("vip").value == null ||
    document.getElementById("vip").value.length == 0
  )
    document.getElementById("vop").value = "Please enter No. of Units";
  else
    document.getElementById("vop").value =
      Math.round(((ip * from) / to) * 100000) / 100000 + " " + totext;
}

function selunit() {
  if (document.getElementById("ut").value == "1") {
    hi();
    uc1();
    len();
  }
  if (document.getElementById("ut").value == "2") {
    hi();
    uc2();
    area();
  }
  if (document.getElementById("ut").value == "3") {
    hi();
    uc3();
    speed();
  }
  if (document.getElementById("ut").value == "4") {
    hi();
    uc4();
    weight();
  }
  if (document.getElementById("ut").value == "5") {
    hi();
    uc5();
    vol();
  }
  
}
window.onload = function () {
  hi();
  uc1();
  len();
};