polyfill-service
Version:
A polyfill combinator
258 lines (215 loc) • 8.04 kB
JavaScript
/**
* Create mappings between the names parsed from useragent to caniuse
* name equivalents. We support the caniuse names listed in the
* `baselineVersion` map below. This module must return one of these
* family names, with a version matching the baseline range, for any
* polyfills to be served.
*
* Multiple names may map to the same canonical caniuse family
*/
'use strict';
const useragent = require('useragent');
// Load additional useragent features: primarily to use: agent.satisfies to
// test a browser version against a semver string
require('useragent/features');
// Longest genuine UA seen so far: 255 chars (Facebook in-app on iOS):
const MAX_UA_LEN = 300;
// Use a local LRU cache rather than the one built into useragent, since that cannot be configured
const cache = require('lru-cache')({
max: 5000
});
const baseLineVersions = {
"ie": ">=7",
"ie_mob": ">=8",
"chrome": "*",
"safari": ">=4",
"ios_saf": ">=4",
"ios_chr": ">=4",
"firefox": ">=3.6",
"firefox_mob": ">=4",
"android": ">=3",
"opera": ">=11",
"op_mob": ">=10",
"op_mini": ">=5",
"bb": ">=6",
"samsung_mob": ">=4"
};
/* Aliases may be expressed in three formats:
1. <detectedfamily>: <targetfamily>
The browser family is renamed, version is maintained
2. <detectedfamily>: [<targetfamily>, <targetmajor>, <targetminor>, <targetpatch>]
The browser family is renamed and the version is set to the one specified
3. <detectedfamily>: { <semver>: [<targetfamily>, <targetmajor>, <targetminor>, <targetpatch>], ... }
Specific version ranges of this family are mapped to the specified browsers
4. <detectedfamily>: <function(uaObj)>
The function is called with the parsed UA object, and must return it (but may modify it first)
*/
const aliases = {
"blackberry webkit": "bb",
"blackberry": "bb",
"pale moon (firefox variant)": "firefox",
"pale moon": "firefox",
"firefox mobile": "firefox_mob",
"firefox namoroka": "firefox",
"firefox shiretoko": "firefox",
"firefox minefield": "firefox",
"firefox alpha": "firefox",
"firefox beta": "firefox",
"microb": "firefox",
"mozilladeveloperpreview": "firefox",
"iceweasel": "firefox",
"opera tablet": "opera",
"opera mobile": "op_mob",
"opera mini": "op_mini",
"chrome mobile": "chrome",
"chrome frame": "chrome",
"chromium": "chrome",
"ie mobile": "ie_mob",
"ie large screen": "ie",
"internet explorer": "ie",
"edge": "ie",
"edge mobile": "ie",
"uc browser": {
"9.9.*": ["ie", 10]
},
"chrome mobile ios": "ios_chr", // comes back as ios_saf
"mobile safari": "ios_saf",
"iphone": "ios_saf", // can't find a uastring which useragent returns iphone as family
"iphone simulator": "ios_saf", // useragent returns either mobile safari or mobile safari uiwebview
"mobile safari uiwebview": "ios_saf",
"mobile safari ui/wkwebview": "ios_saf",
"samsung internet": "samsung_mob",
"phantomjs": ["safari", 5],
"yandex browser": {
"14.10": ["chrome", 37],
"14.8": ["chrome", 36],
"14.7": ["chrome", 35],
"14.5": ["chrome", 34],
"14.4": ["chrome", 33],
"14.2": ["chrome", 32],
"13.12": ["chrome", 30],
"13.10": ["chrome", 28],
"17.9": ["chrome", 60]
},
"opera": {
"20": ["chrome", 33],
"21": ["chrome", 34],
"22": ["chrome", 35],
"23": ["chrome", 36],
"24": ["chrome", 37],
"25": ["chrome", 38],
"26": ["chrome", 39],
"27": ["chrome", 40],
"28": ["chrome", 41],
"29": ["chrome", 42],
"30": ["chrome", 43],
"31": ["chrome", 44],
"32": ["chrome", 45],
"33": ["chrome", 46],
"34": ["chrome", 47],
"35": ["chrome", 48],
"36": ["chrome", 49],
"37": ["chrome", 50],
"38": ["chrome", 51],
"39": ["chrome", 52],
"40": ["chrome", 53],
"41": ["chrome", 54],
"42": ["chrome", 55],
"43": ["chrome", 56],
"44": ["chrome", 57],
"45": ["chrome", 58],
"46": ["chrome", 59],
"47": ["chrome", 60]
},
"googlebot": {
"2.1": ["chrome", 41]
}
};
function UA(uaString) {
// Limit the length of the UA to avoid perf issues in UA parsing
uaString = uaString.substr(0, MAX_UA_LEN);
// The longest string that can possibly be a normalized browser name that we
// support is XXXXXXXXXX/###.###.### (22 chars), so avoid doing the regex if
// the input string is longer than that
let normalized = (uaString.length < 22) && uaString.match(/^(\w+)\/(\d+)(?:\.(\d+)(?:\.(\d+))?)?$/i);
if (!normalized) {
normalized = cache.get(uaString);
}
if (normalized) {
this.ua = new useragent.Agent(normalized[1], normalized[2], (normalized[3] || 0), (normalized[4] || 0));
} else {
/* Remove UA tokens that unnecessarily complicate UA parsing */
// Chrome and Opera on iOS uses a UIWebView of the underlying platform to render
// content. By stripping the CriOS or OPiOS strings, the useragent parser will alias the
// user agent to ios_saf for the UIWebView, which is closer to the actual renderer
uaString = uaString.replace(/((CriOS|OPiOS)\/(\d+)\.(\d+)\.(\d+)\.(\d+)|(FxiOS\/(\d+)\.(\d+)))/, '');
// Vivaldi browser is recognised by UA module but is actually identical to Chrome, so
// the best way to get accurate targeting is to remove the vivaldi token from the UA
uaString = uaString.replace(/ vivaldi\/[\d\.]+\d+/i, '');
// Facebook in-app browser `[FBAN/.....]` or `[FB_IAB/.....]` (see #990)
uaString = uaString.replace(/ \[(FB_IAB|FBAN|FBIOS|FB4A)\/[^\]]+\]/i, '');
// Electron ` Electron/X.Y.Z` (see #1129)
uaString = uaString.replace(/ Electron\/[\d\.]+\d+/i, '');
this.ua = useragent.parse(uaString);
// For improved CDN cache performance, remove the patch version. There are few cases in which a patch release drops the requirement for a polyfill, but if so, the polyfill can simply be served unnecessarily to the patch versions that contain the fix, and we can stop targeting at the next minor release.
this.ua.patch = '0';
// Resolve aliases
this.ua.family = this.ua.family.toLowerCase();
if (aliases[this.ua.family]) {
// Custom aliasing
if (typeof aliases[this.ua.family] === 'function') {
Object.assign(this.ua, aliases[this.ua.family](this.ua));
// Map to different family, use same version scheme
} else if (typeof aliases[this.ua.family] === 'string') {
this.ua.family = aliases[this.ua.family];
// Map to different family with constant version
} else if (Array.isArray(aliases[this.ua.family]) && aliases[this.ua.family].length >= 2) {
const a = aliases[this.ua.family];
this.ua = new useragent.Agent(a[0], a[1], (a[2] || 0), (a[3] || 0));
// Map to different family with per-version mapping
} else if (typeof aliases[this.ua.family] === 'object') {
for (let semverExpr in aliases[this.ua.family]) { // eslint-disable-line prefer-const
if (this.ua.satisfies(semverExpr) && Array.isArray(aliases[this.ua.family][semverExpr])) {
const a = aliases[this.ua.family][semverExpr];
this.ua = new useragent.Agent(a[0], a[1], (a[2] || 0), (a[3] || 0));
break;
}
}
}
}
cache.set(uaString, ["", this.ua.family, this.ua.major, this.ua.minor, this.ua.patch]);
}
}
UA.prototype.getFamily = function() {
return this.ua.family;
};
UA.prototype.getVersion = function() {
return this.ua.toVersion();
};
UA.prototype.satisfies = function() {
return (
this.ua.satisfies.apply(this.ua, arguments) &&
this.ua.family in baseLineVersions &&
this.ua.satisfies(baseLineVersions[this.ua.family])
);
};
UA.prototype.getBaseline = function() {
return baseLineVersions[this.ua.family];
};
UA.prototype.meetsBaseline = function() {
return (this.ua.satisfies(baseLineVersions[this.ua.family]));
};
UA.prototype.isUnknown = function() {
return (Object.keys(baseLineVersions).indexOf(this.ua.family) === -1) || !this.meetsBaseline();
};
UA.normalize = function(uaString) {
if (uaString.match(/^\w+\/\d+(\.\d+(\.\d+)?)?$/i)) {
return uaString.toLowerCase();
}
const ua = new UA(uaString);
return ua.getFamily() + '/' + ua.getVersion();
};
UA.getBaselines = function() {
return baseLineVersions;
};
module.exports = UA;