Entered multiple email id's with comma/semicolon separator in text box to validate using javascript

Hi try below

<asp:button id="btnSendInvite" runat="server" onclientclick="Javascript:return VerifyEmail();" text="Send Invite Now" />

<script type="text/javascript">

function VerifyEmail() {
var ids = document.getElementById('txtInvtMember').value


myArray = ids.split(',');
var i;
for (i = 0; i < myArray.length; i++) {
var emailID = trim(myArray[i]);
if (echeck(emailID) == false) { return false }
}
return true
}

function echeck(str) {

var at = "@"
var dot = "."
var lat = str.indexOf(at)
var lstr = str.length
var ldot = str.indexOf(dot)
if (str.indexOf(at) == -1) {
alert("Invalid E-mail ID: " + str)
return false
}

if (str.indexOf(at) == -1 || str.indexOf(at) == 0 || str.indexOf(at) == lstr) {
alert("Invalid E-mail ID: " + str)
return false
}

if (str.indexOf(dot) == -1 || str.indexOf(dot) == 0 || str.indexOf(dot) == lstr) {
alert("Invalid E-mail ID: " + str)
return false
}

if (str.substring(lat - 1, lat) == dot || str.substring(lat + 1, lat + 2) == dot) {
alert("Invalid E-mail ID: " + str)
return false
}

if (str.indexOf(dot, (lat + 2)) == -1) {
alert("Invalid E-mail ID: " + str)
return false
}

if (str.indexOf(" ") != -1) {
alert("Invalid E-mail ID: " + str)
return false
}

return true
}

function trim(s) {
return rtrim(ltrim(s));
}

function ltrim(s) {
var l = 0;
while (l < s.length && s[l] == ' ')
{ l++; }
return s.substring(l, s.length);
}

function rtrim(s) {
var r = s.length - 1;
while (r > 0 && s[r] == ' ')
{ r -= 1; }
return s.substring(0, r + 1);
}

</script>