使用方法

Gcon.getIcon('https://www.baidu.com/', function(imgUrl) {
  console.log(imgUrl); // https://www.baidu.com/favicon.ico
})

程式碼

(function () {
    'use strict';

    var Gcon = Gcon || {};
    var domainReg = /(.+?:\/\/.+?)\//i;
    var iconTagReg = /<link.+?shortcut.+?>/i;
    var iconUrlReg = /href="(.+?)"/i
 
;

    function getIconFromFile(url, callback) {
        var xhr = null;
        url += '/';
        var iconUrl = url.match(domainReg)[1] + '/favicon.ico';
        if (window.XMLHttpRequest) {
            xhr = new XMLHttpRequest();
        } else if (window.ActiveXObject) {
            xhr = new ActiveXObject("Microsoft.XMLHTTP"
 
);
        }
        if (xhr != null) {
            xhr.onreadystatechange = function () {
                if (this.readyState == 4) {
                    if (this.status == 200) {
                        if (this.responseText) {
                            callback(iconUrl);
                        } else
 
 {
                            getIconFromHtml(url, callback);
                        }
                    } else {
                        getIconFromHtml(url, callback);
                    }
                }
            };
            xhr.open("GET", iconUrl, true);
            xhr.send();
        }
    }

    function getIconFromHtml(url, callback) {
        var xhr = null;
        if (window.XMLHttpRequest) {
            xhr = new XMLHttpRequest();
        } else if (window.ActiveXObject) {
            xhr = new ActiveXObject("Microsoft.XMLHTTP");
        }
        if (xhr != null) {
            xhr.onreadystatechange = function () {
                if (xhr.readyState == 4) {
                    if (xhr.status == 200) {
                        if (this.responseText) {
                            var html = this.responseText;
                            var iconTag = html.match(iconTagReg)[0];
                            iconTag = iconTag.replace(/\s/g, '');
                            var iUrl = iconTag.match(iconUrlReg)[1];
                            callback(iUrl);
                        } else {
                            callback(null);
                        }
                    } else {
                        callback(null);
                    }
                }
            };
            xhr.open("GET", url, true);
            xhr.send();
        }
    }
    Gcon.getIcon = function (url, callback) {
        var icon = '';
        getIconFromFile(url, callback)
    }
    window.Gcon = Gcon;
})();