根据之前的两个答案

维尼修斯·莫赖斯 曾国藩

和文件

Internet Explorer (ie10) Safari(2012。07. 23)。 Firefox(2013。05. 20)。 Chrome(2013。01. 25.)和Chrome(2012。10. 04)。 还有我的一些知识

下面是针对该问题的最佳实现，这意味着如果有一个真正存在的console.log，它将通过console.log填补不存在方法的空白。

例如，对于IE6/7，你可以用alert代替日志记录(愚蠢但有效)，然后包括下面的怪物(我称之为console.js): [请随意删除你认为合适的评论，我把它们留作参考，最小化可以解决它们]:

<!--[if lte IE 7]>
<SCRIPT LANGUAGE="javascript">
    (window.console = window.console || {}).log = function() { return window.alert.apply(window, arguments); };
</SCRIPT>
<![endif]-->
<script type="text/javascript" src="console.js"></script>

和console.js:

    /**
     * Protect window.console method calls, e.g. console is not defined on IE
     * unless dev tools are open, and IE doesn't define console.debug
     */
    (function() {
        var console = (window.console = window.console || {});
        var noop = function () {};
        var log = console.log || noop;
        var start = function(name) { return function(param) { log("Start " + name + ": " + param); } };
        var end = function(name) { return function(param) { log("End " + name + ": " + param); } };

        var methods = {
            // Internet Explorer (IE 10): http://msdn.microsoft.com/en-us/library/ie/hh772169(v=vs.85).aspx#methods
            // assert(test, message, optionalParams), clear(), count(countTitle), debug(message, optionalParams), dir(value, optionalParams), dirxml(value), error(message, optionalParams), group(groupTitle), groupCollapsed(groupTitle), groupEnd([groupTitle]), info(message, optionalParams), log(message, optionalParams), msIsIndependentlyComposed(oElementNode), profile(reportName), profileEnd(), time(timerName), timeEnd(timerName), trace(), warn(message, optionalParams)
            // "assert", "clear", "count", "debug", "dir", "dirxml", "error", "group", "groupCollapsed", "groupEnd", "info", "log", "msIsIndependentlyComposed", "profile", "profileEnd", "time", "timeEnd", "trace", "warn"

            // Safari (2012. 07. 23.): https://developer.apple.com/library/safari/#documentation/AppleApplications/Conceptual/Safari_Developer_Guide/DebuggingYourWebsite/DebuggingYourWebsite.html#//apple_ref/doc/uid/TP40007874-CH8-SW20
            // assert(expression, message-object), count([title]), debug([message-object]), dir(object), dirxml(node), error(message-object), group(message-object), groupEnd(), info(message-object), log(message-object), profile([title]), profileEnd([title]), time(name), markTimeline("string"), trace(), warn(message-object)
            // "assert", "count", "debug", "dir", "dirxml", "error", "group", "groupEnd", "info", "log", "profile", "profileEnd", "time", "markTimeline", "trace", "warn"

            // Firefox (2013. 05. 20.): https://developer.mozilla.org/en-US/docs/Web/API/console
            // debug(obj1 [, obj2, ..., objN]), debug(msg [, subst1, ..., substN]), dir(object), error(obj1 [, obj2, ..., objN]), error(msg [, subst1, ..., substN]), group(), groupCollapsed(), groupEnd(), info(obj1 [, obj2, ..., objN]), info(msg [, subst1, ..., substN]), log(obj1 [, obj2, ..., objN]), log(msg [, subst1, ..., substN]), time(timerName), timeEnd(timerName), trace(), warn(obj1 [, obj2, ..., objN]), warn(msg [, subst1, ..., substN])
            // "debug", "dir", "error", "group", "groupCollapsed", "groupEnd", "info", "log", "time", "timeEnd", "trace", "warn"

            // Chrome (2013. 01. 25.): https://developers.google.com/chrome-developer-tools/docs/console-api
            // assert(expression, object), clear(), count(label), debug(object [, object, ...]), dir(object), dirxml(object), error(object [, object, ...]), group(object[, object, ...]), groupCollapsed(object[, object, ...]), groupEnd(), info(object [, object, ...]), log(object [, object, ...]), profile([label]), profileEnd(), time(label), timeEnd(label), timeStamp([label]), trace(), warn(object [, object, ...])
            // "assert", "clear", "count", "debug", "dir", "dirxml", "error", "group", "groupCollapsed", "groupEnd", "info", "log", "profile", "profileEnd", "time", "timeEnd", "timeStamp", "trace", "warn"
            // Chrome (2012. 10. 04.): https://developers.google.com/web-toolkit/speedtracer/logging-api
            // markTimeline(String)
            // "markTimeline"

            assert: noop, clear: noop, trace: noop, count: noop, timeStamp: noop, msIsIndependentlyComposed: noop,
            debug: log, info: log, log: log, warn: log, error: log,
            dir: log, dirxml: log, markTimeline: log,
            group: start('group'), groupCollapsed: start('groupCollapsed'), groupEnd: end('group'),
            profile: start('profile'), profileEnd: end('profile'),
            time: start('time'), timeEnd: end('time')
        };

        for (var method in methods) {
            if ( methods.hasOwnProperty(method) && !(method in console) ) { // define undefined methods as best-effort methods
                console[method] = methods[method];
            }
        }
    })();

Try

if (!window.console) console = ...

未定义的变量不能直接引用。但是，所有全局变量都是全局上下文(浏览器为窗口)同名的属性，访问未定义的属性是可以的。

或者使用if (typeof console === 'undefined') console =…如果你想避开神奇的变量窗口，请参阅@Tim Down的回答。

注意到OP在IE中使用Firebug，所以假设它是Firebug Lite。当调试器窗口打开时，在IE中定义控制台，这是一种奇怪的情况，但是当Firebug已经在运行时会发生什么呢?不确定，但在这种情况下，"firebugx.js"方法可能是一个很好的测试方法:

来源:

https://code.google.com/p/fbug/source/browse/branches/firebug1.2/lite/firebugx.js?r=187

    if (!window.console || !console.firebug) {
        var names = [
            "log", "debug", "info", "warn", "error", "assert",
            "dir","dirxml","group","groupEnd","time","timeEnd",
            "count","trace","profile","profileEnd"
        ];
        window.console = {};
        for (var i = 0; i < names.length; ++i)
            window.console[names[i]] = function() {}
    }

(更新链接12/2014)

另一种选择是typeof操作符:

if (typeof console == "undefined") {
    this.console = {log: function() {}};
}

还有一种替代方法是使用日志库，比如我自己的log4javascript。

在我的脚本中，我要么使用速记:

window.console && console.log(...) // only log if the function exists

或者，如果不可能编辑每一个console.log行，我创建一个假控制台:

// check to see if console exists. If not, create an empty object for it,
// then create and empty logging function which does nothing. 
//
// REMEMBER: put this before any other console.log calls
!window.console && (window.console = {} && window.console.log = function () {});

您可以在Firefox中直接使用console.log(…)，但不能在ie中使用。在ie中，你必须使用window.console。