Help:ParserFunctions

From Homestar Runner Wiki

This wiki has an extension installed, called ParserFunctions. Here's how to use them:

#expr:

expr solves mathematical expressions. It does not work with strings, if you want to use those, see ifeq. It also only works with numerical entries.

#if:

The if function is an if-then-else system. It measures if the condition string is empty, it does the else text. If it is not empty, it does the than text. The syntax is:

{{#if: <condition string> | <then text> | <else text> }}

Its most common usage is in templates, where if the user defines a parameter, then it shows this text. If the user does not specify it, it shows a default. Example:

{{#if: {{{parameter|}}} | Parameter is defined | Parameter is not defined }}

If the user types {{templatename|parameter=true}} or something similar, the result is "Parameter is defined". However, if they type {{templatename}}, the result it "Parameter is not defined".

This does not solve expressions. For example, if you type {{#if: 30 - 30 = 50 | 1 | 0 }}, the result will be 1, since 30 - 30 = 50 is not empty. If you want to do if-then-else using expressions, see #ifexpr.

#ifeq:

ifeq compares two strings and then does an then-else process. To use:

{{#ifeq: <text 1> | <text 2> | <if equal> | <if not equal> }}

If text 1 and text 2 are equal, then it does the <ifequal> text. Otherwise, it does the <ifnotequal> text.

Some examples:

• {{#ifeq: {{NAMESPACE}} | Help | This page is in the Help Namespace | This page is not in the Help Namespace }} shows up as This page is in the Help Namespace.
• {{#ifeq: 7 | +000007 | Seven = Seven | Seven is not equal to Seven }} shows up as Seven = Seven

ifeq is case-sensitive.

{{#ifeq: capital | Capital | Equal | Not Equal }} shows up as Not Equal.

#ifexist:

ifexist does an if-then-else process depending on if a page exists. Syntax:

{{#ifexist: <page name> | <if exists> | <if does not exist> }}

ifexist does not work with interwiki links.

Example:

{{#ifexist: sbemail | [[Strong Bad Email]] | [[Main Page]] }} gives Strong Bad Email because "sbemail" exists.

#ifexpr:

ifexpr is a combination of if-then-else and expr. It can only be done with numbers, just like expr. Syntax:

{{#ifexpr: <expression> | <if true> | <if false> }}

Some examples:

• {{#ifexpr: 30 / 40 = 120 | yes | no }} shows up as no.
• {{#ifexpr: {{PAGENAME}} = ParserFunctions | This is a help page | No}} shows up as Expression error: Unrecognised word "parserfunctions" because PAGENAME is not a number.

#switch:

switch compares a string against many items, and shows a result if one is true. Syntax:

{{#switch: <value>
| <result 1> = <text if 1 is true>
| <result 2> = <text if 2 is true>
| <result 3> = <text if 3 is true>
| <result 4> = <text if 4 is true>
| #default = <default value if none are true>
}}

"| <result n> = <text if n is true>" can be repeated as many times as neccesary. However, "#default" can only be used once.

It is also possible to have "fall-through":

{{#switch: <value>
| <result 1>
| <result 2>
| <result 3> = <text if 1, 2, or 3 is true>
| <result 4> = <text if 4 is true>
| #default = <default value if none are true>
}}

<result 1> and <result 2> do not have equal signs, and instead will use <result 3>'s text.

#time:

time is used for time and date formatting. It can be used to show the current time or day, or a set time or day in a certain format. Either way, here are the codes (following UTC):

Any text not shown above will come out unmodified, so links and punctuation are possible. Examples:

• {{#time: l j F Y }} generates Wednesday 4 February 2026.
• {{#time: m/Y }} generates 02/2026.
• {{#time: H:i | - 6 hours}} generates 03:36, 6 hours before the current time
• {{#time: l Y-m-d }} generates Wednesday 2026-02-04.
• {{#time: l }} generates Wednesday.
• {{#time: z | 20071031}} generates 303, Halloween day in "z" format

#rand:

rand generates a random number. It has been depreciated in current versions of ParserFunctions, but the HRWiki uses an older version that still has rand. Syntax:

{{#rand: <minimum> | <maximum> }}

The minimum is the smallest number it can generate, the maximum is the largest.

Examples:

• {{#rand: 1 | 50 }} generates 5.
• {{#rand: 1 | 500000 }} generates 371835.
• {{#rand: .1 | .9 }} generates 0, because it cannot do decimals.

See Also

Meta's page on ParserFunctions