Comparar y concatenar cadena javascript

[America|UNK]

Código Javascript:

function _indexOf(arr, c) {
    if (arr.indexOf) return arr.indexOf(c)
    var b = 0
    while( arr[b++] ) if (arr[b] === c) return b
    return -1
}
function Found(arr1,arr2){
    var nuevo = [], d = 0
    while( arr1[d++] ) 
        _indexOf(arr2, arr1[d]) > -1 && nuevo.push( arr1[d] )
    return nuevo
}
var cad1 = '"COD05", "COD02", "COD04", "COD10"'
var cad2 = '"COD01", "COD02", "COD03", "COD04"'
cad1 = cad1.match(/COD\d+/gi)
cad2 = cad2.match(/COD\d+/gi)
 
alert(Found(cad1,cad2).join(','))