// Check browsers
var ua = navigator.userAgent;
var strBrowser;
var nVersion;
var nHit;    // 合致した部分の先頭の文字の添え字

if ((nHit = ua.indexOf("MSIE")) >= 0) {
      strBrowser = "IE";
      nVersion = ua.substr(nHit+5, 3);
} else if ((nHit = ua.indexOf("Netscape")) >= 0) {
      strBrowser = "NN";
      if (ua.charAt(nHit+8) == "6" ) nVersion = ua.substr(nHit+10, 3);
      else                                    nVersion = ua.substr(nHit+ 9,  3);
} else if ((nHit = ua.indexOf("Safari")) >= 0) {
      strBrowser = "Safari";
      nVersion = ua.substr(nHit+7);
} else if ((nHit = ua.indexOf("Opera")) >= 0) {
      strBrowser = "Opera";
      nVersion = ua.substr(nHit+6, 3);
} else if ((nHit = ua.indexOf("Firefox")) >= 0) {
      strBrowser = "Firefox";
      nVersion = ua.substr(nHit+8, 3);
} else if (ua.indexOf("Gecko") >= 0) {
      nHit = ua.indexOf("rv:");
      strBrowser = "Mozilla";
      nVersion = ua.substr(nHit+3, 3);
} else if (ua.indexOf("Mozilla/4") >= 0) {
      strBrowser = "NN";
      nVersion = 4;
} else {
      strBrowser = "";
      nVersion = 0;
}