FireBug 控制台函数说明

原文地址：http://www.joehewitt.com/software/firebug/docs.php

FireBug 是一个非常实用的JavaScript以及DOM查看调试工具，是 Firefox 的一个插件。使用 FireBug 调试 AJAX 应用非常方便，终于可以告别 alert 时代了！

Console Logging 函数

FireBug 为所有 Web 页面提供了一个 console 对象。这个对象有以下函数：

Logging 基础

console.log("message" [,objects]) - 将一个字符串打印到控制台。字符串可以包含任何“String Formatting”小节描述的模式。字符串后面的对象应该用来取代之前字符串中的模式。（译者注：大家用过C里面 printf 吧，效果基本是一样的。）

Logging 等级

通常根据不同的等级来区分Logging的严重程度是很有帮助的。FireBug 提供了4个等级。为了达到视觉分离的效果，这些函数与

log

不同的地方就是它们在被调用的时候会自动包含一个指向代码行数的链接。

console.debug("message" [,objects]) - 记录一个 debug 消息。
console.info("message" [,objects]) - 记录一个信息.
console.warn("message" [,objects]) - 记录一个警告.
console.error("message" [,objects]) - 记录一个错误.

断言

断言是一条确保代码规则的非常好的途径。console 对象包含了一系列各种类型的断言函数，并且允许你编写自己的断言函数。

console.assert(a, "message" [,objects]) - Asserts that an

a

is true.
console.assertEquals(a, b, "message" [,objects]) - Asserts that

a

is equal to

b

.
console.assertNotEquals(a, b, "message" [,objects]) - Asserts that

a

is not equal to

b

.
console.assertGreater(a, b, "message" [,objects]) - Asserts that

a

is greater than

b

.
console.assertNotGreater(a, b, "message" [,objects]) - Asserts that

a

is not greater than

b

.
console.assertLess(a, b, "message" [,objects]) - Asserts that

a

is less than

b

.
console.assertNotLess(a, b, "message" [,objects]) - Asserts that

a

is not less than

b

.
console.assertContains(a, b, "message" [,objects]) - Asserts that

a

is in the array

b

.
console.assertNotContains(a, b, "message" [,objects]) - Asserts that

a

is not in the array

b

.
console.assertTrue(a, "message" [,objects]) - Asserts that

a

is equal to

true

.
console.assertFalse(a, "message" [,objects]) - Asserts that

a

is equal to

false

.
console.assertNull(a, "message" [,objects]) - Asserts that

a

is equal to

null

.
console.assertNotNull(a, "message" [,objects]) - Asserts that

a

is not equal to

null

.
console.assertUndefined(a, "message" [,objects]) - Asserts that

a

is equal to

undefined

.
console.assertNotUndefined(a, "message" [,objects]) - Asserts that

a

is not equal to

undefined

.
console.assertInstanceOf(a, b, "message" [,objects]) - Asserts that

a

is an instance of type

b

.
console.assertNotInstanceOf(a, b, "message" [,objects]) - Asserts that

a

is not an instance of type

b

.
console.assertTypeOf(a, b, "message" [,objects]) - Asserts that the type of

a

is equal to the string

b

.
console.assertNotTypeOf(a, b, "message" [,objects]) - Asserts that the type of

a

is not equal to the string

b

.

测量（Measurement）

下面的一些函数可以让你方便的测量你的一些代码。

console.trace() - 记录执行点的堆栈信息。
console.time("name") - 根据 name 创建一个唯一的计时器。
console.timeEnd("name") - 根据 name 停止计时器，并且记录消耗的时间，以毫秒为单位。
console.count("name") - 记录该行代码执行的次数。

字符串格式化

所有 console 的 logging 函数都可以通过以下模式格式化字符串：

%s - 将对象格式化为字符串。
%d, %i, %l, %f - 将对象格式化为数字。
%o - 将对象格式化成一个指向 inspector 的超链接。
%1.o, %2.0, etc.. - 将对象格式化成包含自己属性的可交互的表格。
%.o - 将对象格式化成具有自身属性的一个数组。
%x - 将对象格式化成一个可交互的 XML 树形结构。
%1.x, %2.x, etc.. - 将对象格式化成一个可交互的 XML 数型结构，并且展开 n 层节点。
如果你需要一个真实的 % 符号，你可以通过一个转移符号就像这样 "/%"。

命令行函数

内建的命令行函数可以通过以下命令行使用：

$("id") - document.getElementById() 的简写。（译者注：跟 prototype.js 学来的吧？）
$$("css") - 返回一个符合 CSS 选择器的元素数组。
$x("xpath") - 返回一个符合 XPath 选择器的元素数组。
$0 - 返回最近被检查（inspected）的对象。
$1 - 返回最近被检查（inspected）的下一个对象。
$n(5) - 返回最近被检查的第n个对象。
inspect(object) - 将对象显示在 Inspector 中。
dir(object) - 返回一个对象的属性名数组。（译者注：跟 Python 学的？）
clear() - 清除控制台信息。
This entry was posted on 星期三, 九月 20th, 2006 at 10:25 am and is filed under JavaScript, Ajax, Web应用. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.

4 Responses to “FireBug 控制台函数说明”

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Firebug adds a global variable named "console" to all web pages loaded in Firefox. This object contains many methods that allow you to write to the Firebug console to expose information that is flowing through your scripts.

console.log(object[, object, ...])

Writes a message to the console. You may pass as many arguments as you'd like, and they will be joined together in a space-delimited line.

The first argument to

log

may be a string containing printf-like string substitution patterns. For example:

console.log("The %s jumped over %d tall buildings", animal, count);

The example above can be re-written without string substitution to achieve the same result:

console.log("The", animal, "jumped over", count, "tall buildings");

These two techniques can be combined. If you use string substitution but provide more arguments than there are substitution patterns, the remaining arguments will be appended in a space-delimited line, like so:

console.log("I am %s and I have:", myName, thing1, thing2, thing3);

If objects are logged, they will be written not as static text, but as interactive hyperlinks that can be clicked to inspect the object in Firebug's HTML, CSS, Script, or DOM tabs. You may also use the %o pattern to substitute a hyperlink in a string.

Here is the complete set of patterns that you may use for string substitution:

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, ...])

Writes a message to the console, including a hyperlink to the line where it was called.

console.info(object[, object, ...])

Writes a message to the console with the visual "info" icon and color coding and a hyperlink to the line where it was called.

console.warn(object[, object, ...])

Writes a message to the console with the visual "warning" icon and color coding and a hyperlink to the line where it was called.

console.error(object[, object, ...])

Writes a message to the console with the visual "error" icon and color coding and a hyperlink to the line where it was called.

console.assert(expression[, object, ...])

Tests that an expression is true. If not, it will write a message to the console and throw an exception.

console.dir(object)

Prints an interactive listing of all properties of the object. This looks identical to the view that you would see in the DOM tab.

console.dirxml(node)

Prints the XML source tree of an HTML or XML element. This looks identical to the view that you would see in the HTML tab. You can click on any node to inspect it in the HTML tab.

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, ...])

Writes a message to the console and opens a nested block to indent all future messages sent to the console. Call

console.groupEnd()

to close the block.

console.groupEnd()

Closes the most recently opened block created by a call to

console.group

.

console.time(name)

Creates a new timer under the given name. Call

console.timeEnd(name)

with the same name to stop the timer and print the time elapsed..

console.timeEnd(name)

Stops a timer created by a call to

console.time(name)

and writes the time elapsed.

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])

Writes the number of times that the line of code where

count

was called was executed. The optional argument

title

will print a message in addition to the number of the count.