文件上传之渐进式增强

function isUploadControlSetup() {
    var setup = false;

    if (window.ActiveXObject) {//ie
        try {
            if (new ActiveXObject("Cxdndctrl.Upload")) {
                setup = true;
            }
        } catch (ex) {
            try {
                if (new ActiveXObject("ExCxdndCtrl.ExUpload")) {
                    setup = true;
                }
            } catch (e) {
                console.log(ex);
                console.log(‘创建ActiveXObject("Cxdndctrl.Upload")及ActiveXObject("ExCxdndCtrl.ExUpload")对象失败！‘);
            }
        }
    } else if (navigator.plugins) {//firefox chrome
        var mimetype = navigator.mimeTypes["application/x-richinfo-cxdnd3"];

        setup = (mimetype && mimetype.enabledPlugin) ? true : false;
    }

    return setup;
}

function getVersionInIE() {
    var version = 0;
    var axo;

    // NOTE : new ActiveXObject(strFoo) throws an exception if strFoo isn‘t in the registry
    try {
        // version will be set for 7.X or greater players
        axo = new ActiveXObject("ShockwaveFlash.ShockwaveFlash.7");
        version = axo.GetVariable("$version");
    } catch (e) {
    }

    if (!version) {
        try {
            // version will be set for 6.X players only
            axo = new ActiveXObject("ShockwaveFlash.ShockwaveFlash.6");

            // installed player is some revision of 6.0
            // GetVariable("$version") crashes for versions 6.0.22 through 6.0.29,
            // so we have to be careful.

            // default to the first public version
            version = "WIN 6,0,21,0";

            // throws if AllowScripAccess does not exist (introduced in 6.0r47)
            axo.AllowScriptAccess = "always";

            // safe to call for 6.0r47 or greater
            version = axo.GetVariable("$version");

        } catch (e) {
        }
    }

    if (!version) {
        try {
            // version will be set for 4.X or 5.X player
            axo = new ActiveXObject("ShockwaveFlash.ShockwaveFlash.3");
            version = axo.GetVariable("$version");
        } catch (e) {
        }
    }

    if (!version) {
        try {
            // version will be set for 3.X player
            axo = new ActiveXObject("ShockwaveFlash.ShockwaveFlash.3");
            version = "WIN 3,0,18,0";
        } catch (e) {
        }
    }

    if (!version) {
        try {
            // version will be set for 2.X player
            axo = new ActiveXObject("ShockwaveFlash.ShockwaveFlash");
            version = "WIN 2,0,0,11";
        } catch (e) {
        }
    }

    if (version !== 0) {
        var match = version.match(/(\d+),(\d+).*$/);

        if (match[0]) {
            version = Number(match[1] + "." + match[2]);
        } else {
            version = 0;
        }
    }

    return version;
}

function getVersionInOthers() {
    var v = 0;
    if (navigator.plugins && navigator.plugins.length > 0 && navigator.plugins["Shockwave Flash"]) {
        var plugins = navigator.plugins["Shockwave Flash"];
        for (var i = 0; i < plugins.length; i++) {
            var swf = plugins[i];
            if (swf.enabledPlugin && (swf.suffixes.indexOf("swf") != -1) && navigator.mimeTypes["application/x-shockwave-flash"]) {
                var match = plugins.description.match(/ (\d+(?:\.\d+)?)/);
                if (match) {
                    var v = parseInt(match[1]);
                    break;
                }
            }
        }
    }
    return v;
}