Javascript email obfuscator

Javascript email obfuscator function:

function obfEm(_a_id, _part1, _part2, _innerHTML, _part3) {
    if(document.getElementById(_a_id)) {
        var txt1 = _part1;
        var txt2 = _part2;
        var txt3 = _part3;
   
        var ar_mt1 = ['m', 'a', 'i'];
        var ar_mt2 = ['l', 't', 'o'];
   
        var em = new Array();
        em[0] = txt1;
        em[1] = '@';
        em[2] = txt2;
        em[3] = '.';
        em[4] = txt3;

        var ems = em.join('');
        var mts = ar_mt1.join('') + ar_mt2.join('');
       
        document.getElementById(_a_id).href = mts + ':' + ems;
        document.getElementById(_a_id).innerHTML = _innerHTML.length > 0 ? _innerHTML : ems;
    }
}

Javascript email obfuscator HTML:

<script type="text/javascript">

obfEm('a1', 'contact', 'office-space', 'person-name-optional', 'com')

</script>

<script type="text/javascript">

obfEm('a2', 'contact', 'office-space', '', 'com')

</script>