how to add data to array and check whethere it exist in arr

in my gridview i have text box for emailid in that i want make validation for same emailid does not submit to db on button click

for that i wrote java script

function OnSubmit() {

debugger;

var Table_Value = new Array();

var j = 1;

var strValue;

var Grdemilid = document.getElementById('ctl00_ContentPlaceHolder1_Grdemilid');

var len = Grdemilid.rows.length;

for (i = 0; i < Grdemilid.rows.length; i++) {

var txtUnitsArray = $("input[id*=txtemailid]");

var txtemailid = new Array(500)

txtemailid= txtUnitsArray[i].value;

}

return false;

}

in that i will get last email id in loop in array .but i want all email id to be added in arrlist can u help me thank you