polyfill.io.js

//
// JavaScript Polyfills ( Simplified Chinese ) 
// https://wangye.org/posts/2022/03/polyfills-in-javascript-for-newer-features.html 
//

var polyfill_features = [ 
  "MediaQueryList.prototype.addEventListener",
  "String.prototype.startsWith",
  "String.prototype.trim", 
  "Element.prototype.classList",
  "document.querySelector",
  "pageYOffset",
  "Array.prototype.forEach",
  "matchMedia",
  "localStorage",
  "URLSearchParams",
  "URL",
  "JSON",
  "Object.entries"
];

var cache_version = "v1";

// minimum browser version requirements
var min_browsers = {
    "Firefox": 80,
    "Edg": 80,
    "Chrome": 80,
    "Safari": 15
};

; (function(window, document, js_features, jsf_version, browsers) {
    var cacheKey = "js-features";

    var JsPolyfill = function(js_features, jsf_version) {
        function getPreDetectedResult() {
            var jsf_a_unsupports = js_features.join("%2C");
            if (window.localStorage) {
                var jsf = window.localStorage.getItem(cacheKey);
                if (jsf !== null && jsf.indexOf("^") > 0) {
                    var jsf_a = jsf.split("^");
                    var jsf_a_version = jsf_a[0];

                    if (jsf_a_version === jsf_version) {
                        if (jsf_a.length > 1) {
                            jsf_a_unsupports = jsf_a[1];
                        } else {
                            jsf_a_unsupports = "";
                        }
                    }
                }
            }

            return jsf_a_unsupports.split("%2C");
        }

        function getUnsupportedJsFeatures() {
            var unsupports = [];
            var jsf_a_features = getPreDetectedResult();
            var jsf_a_prev_features = "#" + js_features.join("#") + "#";

            for (var i = 0; i < jsf_a_features.length; i++) {
                if (jsf_a_prev_features.indexOf("#" + jsf_a_features[i] + "#") === -1) {
                    console.warn("Pollyfill: Unknown or suspicious code detected," +
                                                  " skipped and continue.");
                    continue;
                }

                if ((function() {
                    if (jsf_a_features[i].indexOf("Element.prototype.") === 0) {
                        return (typeof Element === 'undefined' || 
                               !(jsf_a_features[i].substr("Element.prototype.".length)
                                      in Element.prototype));
                    } else {
                        return eval("typeof " + jsf_a_features[i]) === 'undefined';
                    }
                })()) {
                    unsupports.push(jsf_a_features[i]);
                }
            }

            return (unsupports.length > 0) ? unsupports.join("%2C") : "";
        }

        var params = getUnsupportedJsFeatures();
        if (params !== "") {
            window.localStorage &&
                window.localStorage.setItem(cacheKey, jsf_version + "^" + params);

            var url = "https://polyfill.io/v3/polyfill.min.js?features=" + params;
            document.write('<scr' + 'ipt type="text/javascript" src="' + url 
                                            + '" crossorigin="anonymous"><\/scri' + 'pt>');
        } else {
            window.localStorage &&
                window.localStorage.setItem(cacheKey, jsf_version + "^");
        }
    };

    function isBrowserCompatibleWith() {
        if (window.localStorage && 
                window.localStorage.getItem(cacheKey) === (jsf_version + "^")) {
            return true;
        }

        if (typeof browsers === 'object' &&
               window.navigator && window.navigator.userAgent) {
            return (function() {
                var userAgent = window.navigator.userAgent;
                for (key in browsers) {
                    if (userAgent.indexOf(key + '/') !== -1) {
                        var version = userAgent.split(key + '/')[1];
                        if (key == 'Safari') {
                            version = userAgent.split('Version/')[1];
                        }
                        version_a = version.split('.');
                        version_s = parseInt(version_a[0], 10);
                        if (!isNaN(version_s) && version_s >= browsers[key]) {
                            window.localStorage.setItem(cacheKey, jsf_version + "^");
                            return true;
                        }

                        break;
                    }
                }
                return false;
            })();
        } else {
            return false;
        }
    }

    if (!isBrowserCompatibleWith())
        JsPolyfill(js_features, jsf_version);
})(window, document, 
       polyfill_features, cache_version, min_browsers);