This page documents details on JOSM's ​MapCSS implementation.

General Structure

A MapCSS style sheet has rules of the form

selector {
    prop: value;
    /* ... */
    prop: value;
    /* and/or */
    set: class;
    set: .class;
}

The algorithm to find the styles for a given object is like this:

 - for each rule:
     if the selector applies, set the properties from the { } block
 - analyze the final list of properties and generate styles from it

MapCSS uses the comment format of CSS (/* ... */). Note that when commenting out large parts of a MapCSS file, some constructs may cause an unexpected end of the comment, for instance:

/*
*[highway][name =~ /^R(\.|:)? .*/] { /* the end of the regular expression defines the unexpected end of the comment */
        throwWarning: tr("foo");
}
*/

Selectors

Selectors denote the filter expressions of a MapCSS rule. The rule is only applied to a map object, if its selectors match with the object.

Selectors in MapCSS are different from standard CSS for the web. MapCSS only supports a subset of the standard CSS selectors, but extends them with additional selectors required for OSM data.

Some basic examples:

/* applied to ways with a tag highway=residential */
way[highway=residential] {  /*  the styles */}

/* applied to new, closed ways on layer 1, provided they have the tag amenity=parking and access=public, and provided 
 * the zoom level is between 11 and 14 
 */
way|z11-14[amenity=parking][access=public]:closed:new::layer_1 {...}


area[amenity=parking][access=public], area[amenity=parking][!access] {...}
relation[type=route][route=foot] > way::relation_underlay {..}

The different elements (type-, zoom- , condition selector, pseudo classes, layer identifier, grouping and child combinator) are explained below.

Type selector

Selector	Description
*	Matches with any object
node, way, relation	Matches with the osm objects of the given type.
area	Matches with any area regardless of whether the area border is only modelled with a single way or with a set of ways glued together with a relation. area[natural=beach] {...} /* ... is equal to ... */ way[natural=beach], relation[type=multipolygon][natural=beach] {...} Note that area selects unclosed ways as well, so it may be useful to add the :closed pseudo class. The JOSM Validator will give a warning for unclosed ways that have an area style.
meta	The meta selector starts a special rule that should stand at the beginning of the file. It gives some general information on the style sheet. All software that supports MapCSS should be able to parse this sections without errors, so do not use exotic syntax extensions in this part. meta { title: "Parking lanes"; /* title shown in the menu */ icon: "images/logo.png"; /* small icon shown in the menu next to the title */ version: "1.2"; /* the version of the style */ description: "..."; /* one or two sentences of describing the style */ author: "..."; /* the author(s) of the style */ link: "http://..."; /* URL to the web page of the style */ min-josm-version: 6789; /* the minimum JOSM version where this style works */ }
canvas	Some style information not specific to nodes, ways or relations. canvas { fill-color: #ffffea; /* the former background-color is deprecated since r7110 */ default-points: false; default-lines: false; } Key Description Value Format Default Value fill-color Specifies the overall fill/background color (background-color is deprecated since r7110). Color black default-points Whether default point style should be added to nodes where no style applies. Boolean true default-lines Whether default line style should be added to ways where no style applies. Boolean true

Child selector

If a node is part of a way, we say that it is a child of this way. Similarly, if a node, a way, or a relation is a member of a relation, we say, that it is a child of this relation.

In MapCSS you can use a child selector which matches only if both the parent and the child object match.

Example:

/*
 * only matches for a way which is a child of a relation with tags 
 * type=route and route=foot
 */
relation[type=route][route=foot] > way {...}

Notes:

• Zoom selector and Layer identifier are only relevant for the part to the right of the > sign.
• The functions prop() and is_prop_set() are only supported on the right side of the > sign.
• The function parent_tag (see below) can be used to access tags from the parent.
• For compatibility with the MapCSS 0.2 standard, relation[type=route][route=foot] way {/*...*/}, without the greather-than-sign > is supported, too. However, no #Linkselector may be specified in this case.

Parent selector

In addition to child selectors, JOSMs supports the the notion of a parent selector. Note, that parent selectors are a JOSM-specific extension of MapCSS not present in other MapCSS implementations.

Similar to a child selector, a parent selector only matches if if both the parent and the child object match. In contrast to to the child selector, the character < is used.

In contrast to the child selector, the parent object will be "selected". In other words, the properties in the {...}-Declaration Block apply to the object on the right hand side of the "<" sign.

Example:

/*
 * matches for a highway which has at least one node tagged as traffic_calming=*
 */
node[traffic_calming] < way[highway] {...}

Condition selector

Selectors can include a set of conditions. If any of these conditions evaluates to false, the selector doesn't match and the style rule isn't applied.

An attribute condition specifies a condition on a tag of an OSM object.

Operator	Description	Example
=	Exact match of the value.	way[highway=residential] /* without quotes always case insensitive */ node[name="My name"] /* use quotes for if value includes spaces or if case sensitive matching is important */ node["MY_Special_TAG"="another value"] /* use quotes for tag names if case sensitive matching is required */ node["ÖPVN"=tram] /* use quotes for tag keys with special characters */ /* note that these are not common in OSM at the moment */
!=	Value not equal	way[highway!=residential] /* without quotes always case insensitive */ node[name!="My name"] /* use quotes if value includes spaces or if case sensitive matching is important */ node["MY_Special_TAG"!="another value"] /* use quotes for tag names if case sensitive matching is required */ node["name:fr"!="mon nome"] /* use quotes for tag names with special characters like colons*/
<, >, <=, >=	Comparision for numeric values.	node[population > 50000] /* without quotes always case insensitive */ node[ele <= 3000] /* use quotes for if value includes spaces or if case sensitive matching is important */
^=	Prefix match	node[name ^= "myprefix"] /* value starts with 'myprefix' */
$=	Postfix match	node[name $= "mypostfix"] /* value ends with 'mypostfix' */
*=	Substring match	node[name *= "my substring"] /* value contains the substring 'my substring' */
~=	List membership	*[vending~=stamps] /* the tag value for the tag 'vending' consists of a list of ;-separated values */ /* and one of these values is 'stamps' */
=~	​Regular expression match	name[name=~/^My_pattern.*/] /* the value of the tag 'name' matches with the regular expression '^My_pattern.*' */ /* Note, that reqular expressions have to be enclosed in /.../ */ Case-insensitive matching can be enabled via the embedded flag expression (?i) (see ​Pattern.CASE_INSENSITIVE).
!~ (since r6455)	negated ​Regular expression match	*[surface!~/paved|unpaved/]
∈ (​U+2208, since r6609)	element of	node[amenity=parking] ∈ *[amenity=parking] { throwWarning: tr("{0} inside {1}", "amenity=parking", "amenity=parking"); }
⧉ (​U+29C9, since r6613)	crossing	area:closed:areaStyle ⧉ area:closed:areaStyle { throwOther: tr("Overlapping Areas"); }

Since r6554, it is possible to prefix the "value" (i.e., expression after the operator) with a * in order to "de-reference" it (i.e., obtain consider it as another key and obtain its value). Thus, [key1 = *key2] compares the value of key1 with the value of key2, and [key =~ */pattern/] considers the value of the key pattern as a regular expression and matches it against the value of key.

In addition, you can test whether a tag is present or not:

Condition	Example
Presence of tag	way[highway] /* matches any way with a tag 'highway' */ way["VALSOU"] /* use quotes if case sensitive matching is required */ way["name:fr"] /* use quotes if the tag name includes special caracters (white space, colons, etc.) */
Absence of tag	way[!highway] /* matches any way which does not have a tag 'highway' */ way[!"VALSOU"] /* use quotes if case sensitive matching is required */ way[!"name:fr"] /* use quotes if the tag name includes special caracters (white space, colons, etc.) */
Presence of tag by ​Regular expression match (since r6547)	way[/^addr:/] /* matches any `addr:*` key */

You can test whether the the value of a tag is logical truth value. The value is evaluated to true, if it is either "yes", "true", or "1". All other values are evaluated to false.

Condition	Example
Testing for truth value	way[oneway?] /* matches any way with a truth value in the tag 'oneway' */
Testing for false value (since r6513)	way[oneway?!] /* matches any way with a false value in the tag 'oneway' */

Link selector

In a child selector, you can formulate conditions on the link between a parent and a child object.

If the parent is a relation, you can formulate conditions for the role a member objects has in this relation.

relation[type=route] >[role="link"] way {  /* matches any way which is a member of route relation with role 'link' */ 
   color: blue;
}

Operator	Description	Example
=	Exact match of the role name. The name name role is compulsory in this context.	relation >[role=residential] way /* without quotes always case insensitive */ relation >[role="My name"] way /* use quotes for if the role value includes spaces or if case sensitive matching is important */

The operators !=, ^=, $=, *=, and ~= are supported too. Please refer to condition selector operators.

Nodes in ways and members in relations are ordered. You can formulate conditions on the position of a node in a way or a member object in a relation.

relation[type=route] >[index=1] way {  /* matches the first way which is a member of route relation  */ 
   color: blue;
}

Zoom selector

You can decorate a type selector with a zoom selector. The zoom selector restricts the range of zoom levels at which the respective MapCSS rule is applied.

Example	Description
way|z12 {...}	At zoom level 12
way|z13-15 {...}	From 13 to 15
way|z16- {...}	16 and above
way|z-12 {...}	12 and below
way {...}	any zoom level

The precise definition of scale ranges for each zoom level may change in the future. By rule of thumb you can expect to be approximately at zoom level n when imagery displays slippymap tiles of level n.

Pseudo Classes

:closed	true for ways where the first node is the same as the last and for any multipolygon relation
:new	all new objects
:connection	true for nodes that are used by more than one way
:unconnected	true for nodes that are not used by any way (since r6687)
:tagged	What JOSM considers tagged, i.e. an object that with a tag key other than the following: source*, source_ref, note, comment, converted_by, created_by, watch*, fixme, FIXME, description, attribution (version r4008; in this list, * is a glob)
:righthandtraffic	true if there is right-hand traffic at the current location (since r7193); see left-right-hand-traffic for screenshot of areas

You can also negate pseudo classes. E.g. !:new for all old objects.

Layer Identifier

Layers can be used to create more than one style for a single object. Here is an example:

way[highway=secondary] {
    width: 3;
    color: yellow;
}

way[highway=tertiary] {
    width: 2;
    color: orange;
}

way[access][access!=public]::non_public_access_layer {
    width: +2; 
    color:red; 
    dashes: 2; 
    object-z-index:-1.0;
}

way[bridge]::bridge_layer {
    width: +3; 
    color:#000080;
    opacity:0.5;
    object-z-index:1.0; 
}

This draws all secondary and tertiary roads in yellow and orange respectively. Any road with an access tag other than public will get an extra line style below (object-z-index:-1.0;) the main line. If that part of the street happens to be a bridge, it will also get a half transparent blue overlay. The relative width value (width: +2;) refers to the width on the default layer (2 or 3 in this case).

The name for the layer can be any identifier.

default

If you omit the layer in the selector, this is the same as using ::default.

*

In addition, you can use the * layer to override and initialize all layers.
It overrides all existing subparts, so

way::A { a; } 
way::B { b; } 
way::* { c; } 

is equivalent to

way::A { a; } 
way::B { b; } 
way::A { c; } 
way::B { c; }

And it initializes new subparts. In other words:

way::* { a; } 
way::A { b; } 

is equivalent to

way::A {} 
way::* { a; } 
way::A { b; } 

which is in turn the same as

way::A { a; } 
way::A { b; } 

or

way::A { a; b; }

Grouping

Rules with common declaration block can be grouped into one:

area[landuse=forest] { color: green;   width: 2; }
area[natural=wood] { color: green;   width: 2; }

is the same as

area[landuse=forest], area[natural=wood] { color: green;   width: 2; }

Classes

You may assign classes to matched elements, and define other selectors using those classes:

/* assigning classes */
selector {
  set class;
  /* or equivalently */
  set .class;
}

/* matching classes */
way.class, node[foo=bar].class {
  /* ... */
}

Example for assigning/matching a class named path:

way[highway=footway] { set path; color: #FF6644; width: 2; }
way[highway=path]    { set path; color: brown; width: 2; }
way.path { text:auto; text-color: green; text-position: line; text-offset: 5; }

You can also negate classes. E.g. way!.path for all ways, which are not part of the class .path.

Media queries [since 6970]

Media queries are used to skip a section of the style under certain conditions. Typically you want to use a feature which is introduced in a newer version of JOSM, but like to have a fall back style for users of older JOSM clients. Example:

@media (min-josm-version: 9789) {
    way[highway] {
        width: 4;
        color: orange;
    }
    /* fancy new stuff */
    /* ... */
}

@media (max-josm-version: 9788) {
    way[highway] {
        width: 4;
        color: blue;
    }
    /* fall back mode, using more simple features */
    /* ... */
}

The syntax closely matches the official ​css syntax. The following conditions are supported:

Media condition	Description
(min-josm-version: <number>)	Only include @media section when the current version of JOSM is greater than or equal to the specified number.
(max-josm-version: <number>)	Only include @media section when the current version of JOSM is lower than or equal to the specified number.
(user-agent: <string>)	Only include @media section when the name of the editor / renderer matches the given string. In JOSM, the only accepted value is josm.

Conditions can be combined with and:

@media (min-josm-version: 6970) and (max-josm-version: 7014) {
 /* only for JOSM versions 6970 to 7014 */
}

Multiple combined conditions can be chained with a comma (logical or):

@media (min-josm-version: 6970) and (max-josm-version: 7014), (user-agent: myEditor) {
  /* for JOSM version 6970 to 7014 and for the editor called "myEditor" */
}

Since media queries are only supported in JOSM 6970 and later, you should also specify this as minimum JOSM version in the meta selector:

meta {
    min-josm-version: "6970"; /* This style uses media queries */
    /* ... */
}

Style settings

Styles settings are used to provide the user settings to customize a mappaint style. The user can use them in the MapPaint dialog. Style settings are availible since r7450. The internal style provides style settings since r7454. Note that there are plans to extend the implementation of style settings (currently there are only boolean values supported), so the mapcss syntax for style settings could change in the future (see #10435).

create a setting:

setting::highway_casing {
  type: boolean;
  label: tr("Draw highway casing");
  default: true;
}

use a setting:

way[highway][setting("highway_casing")] {
  casing-width: 2;
  casing-color: white;
}

Properties

General properties

Key	Description	Value Format	Default Value
z-index	Specify the order the objects are drawn: The objects with higher z-index are drawn on top of objects with lower z-index	Number (can be negative)	0
major-z-index	Similar to z-index, but it has higher priority than z-index. So if one object has a higher major-z-index than the other, it is drawn on top. If the major-z-index is the same, z-index decides.	Number (can be negative)	Depends on style element: area: 1, casing: 2, left-/right-casing: 2.1, line-pattern: 2.9, line: 3, point: 4, default-point: 4.1, line-text: 4.9, point-text: 5
object-z-index	Similar to z-index, but has lower priority. Controls the painting order for overlapping objects. E.g. for two crossing ways with text: Use z-index or major-z-index if you first want to draw the two lines and then the two captions. Use object-z-index if one of the ways should be completely on top of the other.	Number (can be negative)	0
modifier	Better control, whether a default line / node symbol is generated by JOSM. This happens when there is no proper style (modifier=false) found on any layer.	false or true	false for the default layer and true for any other layer

Icon and symbol styles

Key	Description	Value Format	Default Value
icon-image	The icon at node position	Image	-
icon-opacity	Opacity of the icon image	Opacity	1.0
icon-width	Width of the icon. If only one of the properties icon-width and icon-height is given, the image will be scaled proportionally. The icon will keep the original size, if neither icon-width nor icon-height is set.	Number	-
icon-height	Height of the icon. (See icon-width)	Number	-
symbol-shape	Display a symbol at the position of the node	square, circle, triangle, pentagon, hexagon, heptagon, octagon, nonagon, decagon	-
symbol-size	Size of the symbol	Number, can be relative ("+4")	10
symbol-stroke-width	outline stroke width	Width	1.0 if symbol-stroke-color is set
symbol-stroke-color	line color	Color	#FFC800 if symbol-stroke-width is set
symbol-stroke-opacity	line opacity	Opacity	1.0
symbol-fill-color	fill color for the shape	Color	blue, unless either symbol-stroke-width or symbol-stroke-color is set
symbol-fill-opacity	fill opacity	Opacity	1.0
text-..., font-...	general text & font properties
text-anchor-horizontal	horizontal text label placement	left, center, right	right
text-anchor-vertical	vertical text label placement	above, top, center, bottom, below	bottom

Do not rely on the default values for symbol-... properties (except for opacity). They are intended for "quick & dirty" style sheets and should be set to an explicit value.

Line styles

Key	Description	Value Format	Default Value
width	Line width	Width	-
color	Line color	Color	value of fill-color or (if unset) JOSM's default untagged color (#808080)
opacity	How transparent the line is.	Opacity	1.0
dashes	An array of alternating on/off lengths	list of numbers, e.g. > 15, 5 may be written as expression: > list(3, 4, 5, 6) or the keyword none to turn dashes off	-
dashes-offset	shift the dash pattern by a certain amount	Number (>= 0)	0
dashes-background-color	The color to use in between the dashes (optional)	Color	-
dashes-background-opacity	Opacity value for the dashes background	Opacity	value of opacity
linecap	Shape at the end of the line (see ​here)	none, round, square	none
linejoin	Shape at the line corners	round, miter, bevel	round
miterlimit	Applies for linejoin: miter. Sets the maximum overshoot when line segments meet at a very small angle	Number (>= 1.0)	10.0
offset	Move line to the left or right (when looking in way direction). This could be used to draw multiple lanes for one way or mark left and right side of a way differently.	Number (positive value moves line to the left, negative to the right)	0
text-position	set to line, if text should be drawn along the line	line, center	-
text-..., font-...	general text & font properties
repeat-image	repeated image along a line [since 5801]	Image	-
repeat-image-width	Width of the image (optional, see icon-width) [since 5811]	Number	-
repeat-image-height	Height of the image (optional) [since 5811]	Number	-
repeat-image-align	Alignment of the image. Top-, bottom edge or the (horizontal) center line of the image will be along the line [since 5801]	top, center, bottom	center
repeat-image-offset	Offset from the line [since 5801]	Number	0
repeat-image-spacing	Spacing between repeated images [since 5801]	Number	0
repeat-image-phase	Initial spacing at the beginning of the line [since 5812]	Number	0

All these properties (except for text-... and font-...) exist also with the casing- prefix. The casing is a second independent line element, that is drawn below the normal line and can be used to draw a thin frame around the line in another color.

Key	Description	Value Format	Default Value
casing-width	Width of the border on both sides of the main line. In JOSM < 5214: Total width of the casing	Width (revers to width if relative width is specified)	-
casing-color	Casing color	Color	value of fill-color or (if unset) JOSM's default untagged color (#808080)
casing-opacity	How transparent the casing is.	Opacity	1.0
casing-...	...	...	...

Similar to casing-, there is also the left-casing- and right-casing- prefix. It draws additional lines to the left and to the right of the main line.

Area styles

Key	Description	Value Format	Default Value
fill-color	Color in which to fill the area	Color	-
fill-image	Image pattern	Image	-
fill-opacity	How transparent the fill is; applies to both color and image	Opacity	1.0
text-position	set to center, if text should be drawn in the center of the area	line, center	-
text-..., font-...	general text & font properties

Required properties to create an Area style: fill-color or fill-image

Text & Font properties

Key	Description	Value Format	Default Value
text	How to find the label text. No label is displayed, unless this instruction is present.	auto Derive the text automatically. The default name tags are: "name:"+<LANG>, "name", "int_name", "ref", "operator", "brand" and "addr:housenumber". Configure a list of tag names in the preference "mappaint.nameOrder" in order to change this list. String Denotes the key of the tag whose value is used as text. Expressions You can enter an expression to compute the text to be displayed. Examples: eval("this is a static text") - renderes a static text eval(concat(tag("first"), "-", tag("second"))) - displays the concatenated tags "first" and "second"	-
text-color	the text color	Color	white for lines and nodes, #c0c0c0 for areas (JOSM "text" and "areatext" color preferences)
text-opacity	how transparent the text is	Opacity	1.0
text-offset-x	shift the text horizontally, (not supported for text along line)	Number	0
text-offset-y (can also be written as text-offset)	shift the text vertically, positive values shift the text in upwards direction	Number	0
text-halo-radius	size of text background border (to make text visible on background with a similar color)	Number	-
text-halo-color	color of the text halo	Color	complement of the text color
text-halo-opacity	transparency for the text halo	Opacity	1.0
font-family	font family	String	"Helvetica" (JOSM preference "mappaint.font")
font-size	font size	Number	8 (JOSM preference "mappaint.fontsize")
font-weight	bold or not	bold, normal	normal
font-style	italic or not	italic, normal	normal

Width

• 14.0 (any positive number)
• default (use JOSM's default line width, which is 2, but can be configured)
• thinnest (draws the line as thin as possible)
• +3 (with plus sign in front) adds the amount to the width on the default layer. This applies only for styles that are not on the default layer, e.g. highlights. Another way to write this would be prop("width","default")+3. For casing-width, this refers to the width value on the same layer.

Image

See Help/Styles/Images.

Color

• named color as found in ​this list
• html style: #RRGGBB, #RGB, #RRGGBBAA
• rgb(/*r*/, /*g*/, /*b*/) - rgb value with arguments from 0.0 to 1.0
• rgba(/*r*/, /*g*/, /*b*/, /*alpha*/) - rgb value with alpha
• hsb_color(/*hue*/, /*saturation*/, /*brightness*/) - color from HSB color space

Opacity

• from 0.0 (transparent) to 1.0 (opaque)

String

• any character sequence, in quotes, e.g. "images/fill.png". If the string is an identifier, quotes are optional. (Quote and backslash sign can be escaped.)

Number

• integer or floating point (in simple form e.g. 0.3). In general can be negative, but most properties do not support negative numbers
• has a special meaning if you put a "+" sign in front (relative width)

Eval expressions

See Javadoc of Functions for the up-to-date list of functions supported by JOSM's MapCSS implementation.

+, -, *, /

arithmetic operations

||, &&, !

boolean operations

<, >, <=, >=, ==

comparison operators

asin, atan, atan2, ceil, cos, cosh, exp, floor, log, max, min, random, round, signum, sin, sinh, sqrt, tan, tanh

the usual meaning, ​details

cond(b, fst, snd)

b ? fst : snd

if (b) then fst else snd

list(a, b, ...)

create list of values, e.g. for the dashes property

get(lst, n)

get the nth element of the list lst (counting starts at 0) [since 5699]

split(sep, str)

splits string str at occurrences of the separator string sep, returns a list [since 5699]

prop(p_name)

value of the property p_name of the current layer, e.g. prop("width")

prop(p_name, layer_name)

property from the layer layer_name

is_prop_set(p_name)

true, if property p_name is set for the current layer

is_prop_set(p_name, layer_name)

true, if property p_name is set for the layer layer_name

tag(key_name)

get the value of the key key_name from the object in question

parent_tag(key_name)

get the value of the key key_name from the object's parent(s)

has_tag_key(key_name)

true, if the object has a tag with the given key

rgb(r, g, b)

create color value (arguments from 0.0 to 1.0)

hsb_color(h, s, b)

create color from hue, saturation and brightness (arguments from 0.0 to 1.0) [since 6899]

red(clr), green(clr), blue(clr)

get value of color channels in rgb color model

alpha(clr)

get the alpha value of the given color [since 6749]

length(str)

length of a string

count(lst)

length of a list, i.e., counts its elements [since 7162]

length(lst)

length of a list [since 5699] – deprecated since 7162

any(obj1, obj2, ...)

returns the first object which is not null (formerly coalesce, [since 7164])

concat(str1, str2, ...)

assemble the strings to one

join(sep, str1, str2, ...)

join strings, whith sep as separator [since 6737]

JOSM_search("...")

true, if JOSM search applies to the object

tr(str, arg0, arg1, ...)

translate from English to the current language (only for strings in the JOSM user interface) [since 6506]

regexp_test(regexp, string)

test if string matches pattern regexp [since 5699]

regexp_test(regexp, string, flags)

test if string matches pattern regexp; flags is a string that may contain "i" (case insensitive), "m" (multiline) and "s" ("dot all") [since 5699]

regexp_match(regexp, string)

Tries to match string against pattern regexp. Returns a list of capture groups in case of success. The first element (index 0) is the complete match (i.e. string). Further elements correspond to the bracketed parts of the regular expression. [since 5701]

regexp_match(regexp, string, flags)

Tries to match string against pattern regexp. Returns a list of capture groups in case of success. The first element (index 0) is the complete match (i.e. string). Further elements correspond to the bracketed parts of the regular expression. Flags is a string that may contain "i" (case insensitive), "m" (multiline) and "s" ("dot all") [since 5701]

substring(str, idx)

return the substring of str, starting at index idx (0-indexed) [since 6534]

substring(str, start, end)

return the substring of str, starting at index start (inclusive) up to end (exclusive) (0-indexed) [since 6534]

replace(string, old, new)

Replaces any occurrence of the substring old within the string string with the text new

osm_id()

returns the OSM id of the current object [since 5699]

URL_encode(str)

​percent-encode a string. May be useful for data URLs [since 6805]

XML_encode(str)

escape special characters in xml. E.g. < becomes <, other special characters: >, ", ', &, \n, \t and \r [since 6809]

CRC32_checksum(str)

calculate the CRC32 checksum of a string (result is an integer from 0 to 2³²-1) [since 6908]

is_right_hand_traffic() [since 7193]

Check if there is left-hand or right-hand traffic at the current location.

number_of_tags() [since 7237]

returns the number of tags for the current OSM object

print(o) [since 7237]

prints a string representation of o to the command line (for debugging)

println(o) [since 7237]

prints a string representation of o to the command line, followed by a new line (for debugging)

JOSM_pref(key, default) [since 7238, with restrictions since 3856]

Get value from the JOSM advanced preferences. This way you can offer certain options to the user and make the style customizable. It works with strings, numbers, colors and boolean values.
[This function exists since version 3856, but with some restrictions. JOSM_pref always returns a string, but in version 7237 and earlier, the automatic conversion of string to boolean and color was not working. You can use the following workarounds for boolean values and color in version 7237 and earlier: cond(JOSM_pref("myprefkey", "true")="true", "X", "O") and html2color(JOSM_pref("mycolor", "#FF345611")). These explicit conversions should be no longer necessary in version 7238 and later. Automatic conversion to a number works in any version.]

setting() [since 7450]

to use a style setting

Examples

• circle symbol for house number with size depending of the number of digits

  node[addr:housenumber] { 
      symbol-shape: circle; 
      symbol-size: eval((min(length(tag("addr:housenumber")), 3) * 5) + 3); 
      symbol-fill-color: #B0E0E6; 
  
      text: "addr:housenumber"; 
      text-anchor-horizontal: center; 
      text-anchor-vertical: center; 
      text-offset-x: -1; 
      text-offset-y: -1; }
      
  node[addr:housenumber]::hn_casing { 
      z-index: -100; 
      symbol-shape: circle; 
      symbol-size: +2; 
      symbol-fill-color: blue; 
  }
  

• invert colors

  *::* {
      color: eval(rgb(1 - red(prop(color)), 1 - green(prop(color)), 1 - blue(prop(color))));
      fill-color: eval(rgb(1 - red(prop(fill-color)), 1 - green(prop(fill-color)), 1 - blue(prop(fill-color))));
  }
  

• random stuff

  way {
      width: eval(random() * 20);
      color: eval(rgb(random(), random(), random()));
  }
  

• regexp matching example: change "nameXXXsubname" to "name::subname"

  *[name=~/.+XXX.+/] 
  {
      _match: regexp_match("(.+?)XXX(.+)", tag("name"));
      text: concat(get(prop("_match",1), "::", get(prop("_match"),2));
  }
  

• paint buildings in different colors according to street in the address tags

  area[building][addr:street] {
      fill-color: hsb_color(CRC32_checksum(tag("addr:street"))/4294967296.0, 0.9, 0.7);
      fill-opacity: 0.8;
  }
  

Compatibility notes

MapCSS 0.2

Grammar

• way[oneway=yes] does not have any magic, you can use way[oneway?] instead
• no @import
• JOSM does not require eval(...) to be wrapped around expressions, but for compatibility with other MapCSS implementations you should write it out.

Properties

At the moment, JOSM does not support the following properties:

line:

image

label:

font-variant, text-decoration, text-transform, max-width

shield:

not supported

Halcyon (Potlatch 2)

• Text label is placed in the center of the icon. For compatibility with Halcyon put

  node { text-anchor-vertical: center; text-anchor-horizontal: center; }
  

  at the beginning of your style sheet.
• standard z-index in Halcyon is 5, but it is 0 in JOSM
• image: circle; corresponds to symbol-shape: circle;

Kothic

• Kothic has support for eval, which probably differs from JOSM's eval.
• Kothic understands units, whereas JOSM always calculates in pixel.
• The extrusion features are not available in JOSM

Ceyx

• seems to have [tunnel=1] instead of [tunnel=yes] (Halcyon) or [tunnel?] (JOSM)