function extract_uppercase(s) {
var len = s.length;
var upper_s = "";
for (var i = 0; i < len; i++) {
if (s[i] >= 'A' && s[i] <= 'Z')
upper_s += s[i];
}
return upper_s;
}
var s = "JAjaVvAaSscCRripItPT"; // JAVASCRIPTjavascript
var uc = extract_uppercase(s);
document.write(uc);
/*
run:
JAVASCRIPT
*/