转自：http://www.cnblogs.com/flykye/archive/2008/10/03/1303367.html
每个用Firefox加载的页面，Firebug都添加了一个全局变量console，通过这个变量的若干方法，你可以通过脚本向控制台输出各种调试信息。
console.log(object[, object, ...])
往控制台写一条信息，可以有多个参数，甚至可以像printf那样格式化出去，例如
console.log("The %s jumped over %d tall buildings", animal, count);
或者这样：
console.log("The", animal, "jumped over", count, "tall buildings");
console.log("I am %s and I have:", myName, thing1, thing2, thing3);
下面是格式化参数表：
| String Substitution Patterns | |
| %s | String |
| %d, %i | Integer (numeric formatting is not yet supported) |
| %f | Floating point number (numeric formatting is not yet supported) |
| %o | Object hyperlink |
console.debug(object[, object, ...])
向控制台输出一条信息，同时包含了跳往调用行的链接
console.info(object[, object, ...])
向控制台输出一条信息，前面显示“信息”图标，同样包含了跳往调用行的链接
console.warn(object[, object, ...])
向控制台输出一条信息，前面显示“警告”图标，同样包含了跳往调用行的链接
console.error(object[, object, ...])
向控制台输出一条信息，前面显示“错误”图标，同样包含了跳往调用行的链接
console.assert(expression[, object, ...])
校验是否符合表达式，如果不符合，将向控制台输出错误信息，并且抛出异常
console.dir(object)
输出对象的所有属性，可以在DOM标签中看到详细信息
console.dirxml(node)
输出HTML或XML元素的XML代码树，可以再HTML中查看详细的情况
console.trace()
Prints an interactive stack trace of JavaScript execution at the point where it is called.
The stack trace details the functions on the stack, as well as the values that were passed as arguments to each function. You can click each function to take you to its source in the Script tab, and click each argument value to inspect it in the DOM or HTML
tabs.
console.group(object[, object, ...])
分组输出，和console.groupEnd()配合使用，知道下一个console.groupEnd()出现，就闭合分组
console.groupEnd()
和console.group()配合使用
console.time(name)
创建一个定时器，知道调用console.time(name)，才停止该定时器计时
console.timeEnd(name)
和console.time(name)配合使用
console.profile([title])
Turns on the JavaScript profiler. The optional argument title would contain the text to be printed in the header of the profile report
console.profileEnd()
Turns off the JavaScript profiler and prints its report
console.count([title])
计数器，每执行一次,该title的值就累加1