Difference between revisions of "GM log"

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(Update for 4.0)
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As of Greasemonkey 4.0, this method has been removed.  
You should use the [https://developer.mozilla.org/en-US/docs/Web/API/console.log console] instead.
== Description ==
This [[API_reference|API]] method allows script authors simple access to logging informational messages in the Error Console.
If you aren't seeing your messages, make sure you navigate to [[mozillazine:About:config|about:config]], and change the values of <code>javascript.options.showInConsole</code> and <code>javascript.options.strict</code> to true. This can be helpful for debugging.
The output produces the namespace, the name of the script, and the string.
For example:
#namespace/myScript: Hello World!
[[#Examples|Examples]] | [[#GM_log_and_Firebug|GM_log and Firebug]] | [[#Notes|Notes]]
== Syntax ==
'''GM_log(''' ''message'' ''')'''
:Value: Function
:Returns: undefined
:Compatibility: [[Version_history#0.3_beta|Greasemonkey 0.3b+]]
:{| cellpadding="5" style="border-style:solid; background:#FFFFE0;"
|+ Parameters
| <code><span style="background:#FFFFE0;">[[#message |message]]</span></code>
:* All properties are optional except [[#message|message]].
=== Properties ===
==== <code>message</code> ====
:Value: String, Integer<sup>[1]</sup> or Boolean<sup>[1]</sup>
:Usage: <code>'''message''' = "ARGHHH!";</code>
:* Message to send to the JavaScript error console.
:* <sup>[1]</sup> While the value may be a non-string, it will convert the argument to a string. There may also be some instances of visual clipping on large numerical values during conversion.  This is a feature present in Mozilla based JavaScript console logging.
[[#top|top]] | [[#Syntax|back]]''
== Examples ==
{{Core samp |1=<pre style="border: none; margin: inherit;">
GM_log("Hello, World!");
{{Core samp |1=<pre style="border: none; margin: inherit;">
GM_log("Warning, " + someInputField.value + "!");
== GM_log and Firebug ==
Since [https://addons.mozilla.org/firefox/addon/1843 Firebug] 1.0, <code>extensions.firebug.showChromeMessages</code> must be set to <code>true</code> for GM_log messages to show up in the Firebug console.
It is also recommended to enable <code>extensions.firebug.showChromeErrors</code>, as doing so will reveal syntax errors and script breaks.
This can be done from <code>about:config</code>, or from the Firebug GUI. Go to the "Console" tab, then click the arrow next to the tab's name, and ensure that "Show Chrome Errors" and "Show Chrome Messages" are checked.
However, one should note that since <code>GM_log</code> converts any passed parameter to a string, and works from the Chrome, it would be more advisable to simply use <code>console.log</code>, which will allow you to take advantage of Firebug's DOM Inspector on the logged objects.

Latest revision as of 10:03, 3 November 2017

As of Greasemonkey 4.0, this method has been removed. You should use the console instead.