console 命令行工具 X clear

console

function detectBrowser() {
  var browser = navigator.appName
  var b_version = navigator.appVersion
  var version = parseFloat(b_version) if ((browser == "Netscape" || browser == "Microsoft Internet Explorer") && (version >= 4)) {
    alert("您的浏览器已经很棒了！")
  } else {
    alert("您的浏览器需要升级了！")
  }
}

<body onload="detectBrowser()">
</body>