// ページトップに戻る

var USER_AGENT = getAgentName();

function getAgentName() {

  var userAgent = navigator.userAgent;
  var charIndex;
  var majorVersion;

  charIndex = userAgent.indexOf("MSIE");

  if(charIndex) {
        majorVersion = userAgent.charAt(charIndex + 4 + 1);
        if(majorVersion > 4) {
          return("IE5");
        } else if (majorVersion == 4) {
          return("IE4");
        }
  }

  charIndex = userAgent.indexOf("Mozilla");

  majorVersion = userAgent.charAt(charIndex + 7 + 1);

  if(majorVersion > 4) {
        return("NN5");
  } else if (majorVersion == 4) {
        return("NN4");
  }

  return("Unknown");
}

function getWindowYOffset() {
  if(USER_AGENT == "IE5" || USER_AGENT == "IE4") {
        return document.body.scrollTop;
  } else if (USER_AGENT == "NN5" || USER_AGENT == "NN4") {
        return window.pageYOffset;
  } else {
        return 0;
  }
}

var waitTimer;

function jumpTo(dstY, srcY, scrollRate, waitMillSec) {
  if(waitTimer) {
        clearTimeout(waitTimer);
  }

  if( ! dstY || dstY < 0 ) {
        dstY = 0;
  }

  if( ! srcY ) {
        srcY = 0 + getWindowYOffset();
  }

  if( ! scrollRate ) {
        scrollRate = 5;
  }

  if( ! waitMillSec ) {
        waitMillSec = 20;
  }

  srcY += (dstY - getWindowYOffset()) / scrollRate;

  if(srcY < 0) {
        srcY = 0;
  }

  posY = Math.floor(srcY);
  window.scrollTo(0, posY);

  if(posY != dstY) {
        waitTimer = setTimeout("jumpTo("+ dstY +", "+ srcY +", "+ scrollRate +", "+ waitMillSec +")", waitMillSec);
  } else if(posY == dstY) {
        clearTimeout(waitTimer);
  } else if(posY < 1) {
        window.scroll(0, 0);
  }
}

function gotoppage(){
  jumpTo(0, 0, 7, 5);
}