Make whole javascript read character utf-8 or iso-8859-1

I have a js file, which I minify to perform the due tasks. What happens is that whenever I add this js to my pages, where it is called, the characters of the Portuguese language are unreadable. So I think it's missing the UTF-8 or ISO-8859-1 . But the question is, how do I place these calls in a single place in my js file, so that any function within the file makes use of those includes. A single reading. I do not want every method I put this call on unless I can not. Example below, I put only part of my js , start and part of one of the existing functions:

var tituloMultiBrowser;

(function () {
    window.showModalDialog = window.showModalDialog || function (url, arg, opt) {
        url = url || '';                                     //URL
        arg = arg || null;                                   //Argumentos
        opt = opt || 'dialogWidth:300px;dialogHeight:200px'; //Opções: dialogTop;dialogLeft;dialogWidth;dialogHeight/CSS styles

        //Função Chamadora
        var caller = showModalDialog.caller.toString();

        var doc;

        var i = 0;

        if (window.parent.name == 'JANELASIS') {
            doc = window.parent.document;
        }
        else {
            var janela = window.parent.name;
            var janelaPai = window.parent;
            while (janela != 'JANELASIS' && i <= 20) {
                janelaPai = janelaPai.parent;
                janela = janelaPai.parent.name;
                i++;
            }
            doc = janelaPai.parent.document;
        }
..............................
}