Determine if the string emailaddr is a valid email format

String

/**
* Determine if the string emailaddr is a valid email format
* Main judgment ' @ ' and '. ' Whether it appears, and the location of both
* @param emailaddr Input Email address
* @return True/false.
*/

function Emailcheck (EMAILADDR)
{
if ((emailaddr = null) | | (Emailaddr.length < 2)) return false;

Need to appear ' @ ' and not in first character.
var APos = Emailaddr.indexof ("@", 1);

if (APos < 0)
{
return false;
}

'. ' After ' @ ', and not immediately thereafter.
if (Emailaddr.indexof (".", apos+2) < 0)
{
return false;
}

return true;
}