(Javascript) replaceHTML ignorando HTML

/*
*
* Função BETA
* Fazer substituição de textos, ignorando os caracteres HTML!
*/

function replaceHTML(text, textReplace){

    var node = document.body.textContent;


    var n = node.search(text) ;

    var c = 0;

    var i = -1;

    var z = 0;

    var f = 0;

    if(n != -1) {


        var html =  document.body.innerHTML;

        var arr = html.split(' ');

        for(var x = 0; x < arr.length; x++) {


            if(!isset(arr[x])) continue;

            z += (x + arr[x].length);

            idx = arr[x].replace(/<[^>]+>/ig,'');


            if(idx.length == 0) continue;

            t = true;

            b = z;
            for( ; b > -1; b--) {

                if(html[b] == '<')  {
                    t = false;
                }

                if(html[b] == '>') {
                    break;
                }


            }

            for(b = z; b < html.length; b++) {

                if(html[b] == '>') break;

                z ++;
            }

            if(idx.search(text.split(' ')[c]) != -1) {


                if( c == 0 ) i = z - (x + arr[x].length);


                c ++;


                if( c == text.split(' ').length   ) {
                    f = z ;

                    break;
                }

            }
            else
            {
                i = -1;
                c = 0;
            }

        }

        if(i != -1) {


            html = document.body.innerHTML;


            output = "";


            output = html.substr(0, i) + textReplace + html.substr(f);





             document.body.innerHTML = (output);

        }

    }


}