DamonOehlman/detect-browser

https://github.com/DamonOehlman/detect-browser

detect-browser

This is a package that attempts to detect a browser vendor and version (in a semver compatible format) using a navigator useragent in a browser or process.version in node.

这个包使用浏览器中的navigator useragent或node中的process.version检测浏览器厂商和版本(与semver兼容的格式)

Example Usage

const { detect } = require('detect-browser');
const browser = detect();

// handle the case where we don't detect the browser
if (browser) {
  console.log(browser.name);
  console.log(browser.version);
  console.log(browser.os);
}

Or you can use a switch statement:

const { detect } = require('detect-browser');
const browser = detect();

// handle the case where we don't detect the browser
switch (browser && browser.name) {
  case 'chrome':
  case 'firefox':
    console.log('supported');
    break;

  case 'edge':
    console.log('kinda ok');
    break;

  default:
    console.log('not supported');
}

看下图控制器第一行的输出我们就能够看见得到的是{name : "chrome",version : "70.0.3538", os : "Mac OS"}

Adding additional browser support

The current list of browsers that can be detected by detect-browser is not exhaustive. If you have a browser that you would like to add support for then please submit a pull request with the implementation.

但是目前能够被detect-browser这个库检测到的浏览器列表还不够详尽。如果你有想要加入的浏览器，那么就请提交一个实现的请求

Creating an acceptable implementation requires two things需要两样东西:

1. A test demonstrating that the regular expression you have defined identifies your new browser correctly. Examples of this can be found in the test/logic.js file.test测试中阐述了你用来正确识别你的浏览器的自定义的正则表达式，例子如test/logic.js，看下面
   

2. Write the actual regex to the index.js file. In most cases adding the regex to the list of existing regexes will be suitable (if usage of detect-brower returns undefined for instance), but in some cases you might have to add it before an existing regex. This would be true for a case where you have a browser that is a specialised variant of an existing browser but is identified as the non-specialised case.在index.js中写下真是的正则表达式。在大多数情况下列表中已存在的正则表达式与添加进的是相配的，但是在一些情况下你就必须要将其添加在已存在的正则表达式之前。如果您的浏览器是现有浏览器的特殊版本，但被识别为非特殊的，那么这种情况就会发生

When writing the regular expression remember that you would write it containing a single capturing group which captures the version number of the browser.

在编写正则表达式时，请记住，您将编写包含捕获浏览器版本号的单个捕获组的表达式

 detect-browser/index.js

function detect() {
  if (typeof navigator !== 'undefined') {//下面图中有显示navigator
    return parseUserAgent(navigator.userAgent);//navigator.userAgent结果为：Mozilla/5.0 (Macintosh; Intel Mac OS X 10_13_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/70.0.3538.77 Safari/537.36
  }

  return getNodeVersion();
}

function detectOS(userAgentString) {
  var rules = getOperatingSystemRules();//匹配操作系统的正则表达式
  var detected = rules.filter(function (os) {
    return os.rule && os.rule.test(userAgentString);
  })[0];

  return detected ? detected.name : null;
}

function getNodeVersion() {
  var isNode = typeof process !== 'undefined' && process.version;
  return isNode && {
    name: 'node',
    version: process.version.slice(1),
    os: process.platform
  };
}

function parseUserAgent(userAgentString) {
  var browsers = getBrowserRules();//得到浏览器的正则表达式
  if (!userAgentString) {
    return null;
  }

  var detected = browsers.map(function(browser) {
    var match = browser.rule.exec(userAgentString);
    var version = match && match[1].split(/[._]/).slice(0,3);

    if (version && version.length < 3) {
      version = version.concat(version.length == 1 ? [0, 0] : [0]);
    }

    return match && {
      name: browser.name,
      version: version.join('.')
    };
  }).filter(Boolean)[0] || null;

  if (detected) {
    detected.os = detectOS(userAgentString);
  }

  if (/alexa|bot|crawl(er|ing)|facebookexternalhit|feedburner|google web preview|nagios|postrank|pingdom|slurp|spider|yahoo!|yandex/i.test(userAgentString)) {
    detected = detected || {};
    detected.bot = true;
  }

  return detected;
}

function getBrowserRules() { //返回相应的浏览器的正则表达式
  return buildRules([
    [ 'aol', /AOLShield/([0-9._]+)/ ],
    [ 'edge', /Edge/([0-9._]+)/ ],
    [ 'yandexbrowser', /YaBrowser/([0-9._]+)/ ],
    [ 'vivaldi', /Vivaldi/([0-9.]+)/ ],
    [ 'kakaotalk', /KAKAOTALKs([0-9.]+)/ ],
    [ 'samsung', /SamsungBrowser/([0-9.]+)/ ],
    [ 'chrome', /(?!Chrom.*OPR)Chrom(?:e|ium)/([0-9.]+)(:?s|$)/ ],
    [ 'phantomjs', /PhantomJS/([0-9.]+)(:?s|$)/ ],
    [ 'crios', /CriOS/([0-9.]+)(:?s|$)/ ],
    [ 'firefox', /Firefox/([0-9.]+)(?:s|$)/ ],
    [ 'fxios', /FxiOS/([0-9.]+)/ ],
    [ 'opera', /Opera/([0-9.]+)(?:s|$)/ ],
    [ 'opera', /OPR/([0-9.]+)(:?s|$)$/ ],
    [ 'ie', /Trident/7.0.*rv:([0-9.]+).*).*Gecko$/ ],
    [ 'ie', /MSIEs([0-9.]+);.*Trident/[4-7].0/ ],
    [ 'ie', /MSIEs(7.0)/ ],
    [ 'bb10', /BB10;sTouch.*Version/([0-9.]+)/ ],
    [ 'android', /Androids([0-9.]+)/ ],
    [ 'ios', /Version/([0-9._]+).*Mobile.*Safari.*/ ],
    [ 'safari', /Version/([0-9._]+).*Safari/ ],
    [ 'facebook', /FBAV/([0-9.]+)/],
    [ 'instagram', /Instagrams([0-9.]+)/],
    [ 'ios-webview', /AppleWebKit/([0-9.]+).*Mobile/]
  ]);
}

function getOperatingSystemRules() {//匹配操作系统的正则表达式
  return buildRules([
    [ 'iOS', /iP(hone|od|ad)/ ],
    [ 'Android OS', /Android/ ],
    [ 'BlackBerry OS', /BlackBerry|BB10/ ],
    [ 'Windows Mobile', /IEMobile/ ],
    [ 'Amazon OS', /Kindle/ ],
    [ 'Windows 3.11', /Win16/ ],
    [ 'Windows 95', /(Windows 95)|(Win95)|(Windows_95)/ ],
    [ 'Windows 98', /(Windows 98)|(Win98)/ ],
    [ 'Windows 2000', /(Windows NT 5.0)|(Windows 2000)/ ],
    [ 'Windows XP', /(Windows NT 5.1)|(Windows XP)/ ],
    [ 'Windows Server 2003', /(Windows NT 5.2)/ ],
    [ 'Windows Vista', /(Windows NT 6.0)/ ],
    [ 'Windows 7', /(Windows NT 6.1)/ ],
    [ 'Windows 8', /(Windows NT 6.2)/ ],
    [ 'Windows 8.1', /(Windows NT 6.3)/ ],
    [ 'Windows 10', /(Windows NT 10.0)/ ],
    [ 'Windows ME', /Windows ME/ ],
    [ 'Open BSD', /OpenBSD/ ],
    [ 'Sun OS', /SunOS/ ],
    [ 'Linux', /(Linux)|(X11)/ ],
    [ 'Mac OS', /(Mac_PowerPC)|(Macintosh)/ ],
    [ 'QNX', /QNX/ ],
    [ 'BeOS', /BeOS/ ],
    [ 'OS/2', /OS/2/ ],
    [ 'Search Bot', /(nuhk)|(Googlebot)|(Yammybot)|(Openbot)|(Slurp)|(MSNBot)|(Ask Jeeves/Teoma)|(ia_archiver)/ ]
  ]);
}

function buildRules(ruleTuples) {
  return ruleTuples.map(function(tuple) {
    return {
      name: tuple[0],
      rule: tuple[1]
    };
  });
}

module.exports = {
  detect: detect,
  detectOS: detectOS,
  getNodeVersion: getNodeVersion,
  parseUserAgent: parseUserAgent
};

detect-browser/test/logic.js

使用例子来进行说明某类userAgent会检测出什么样的结果：

var test = require('tape');
var { parseUserAgent } = require('../');

function assertAgentString(t, agentString, expectedResult) {
  t.deepEqual(parseUserAgent(agentString), expectedResult);
}

test('detects Chrome', function(t) {
  assertAgentString(t,
    'Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/50.0.2661.102 Safari/537.36',
    { name: 'chrome', version: '50.0.2661', os: 'Linux' }
  );

  assertAgentString(t,
    'Mozilla/5.0 (Windows NT 6.1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/41.0.2228.0 Safari/537.36',
    { name: 'chrome', version: '41.0.2228', os: 'Windows 7' }
  );

  t.end();
});
test('handles no browser', function(t) {
    assertAgentString(t,
        null,
        null
    );

    t.end();
});