CSSStyleDeclaration

CSS object model css-object-model

Baseline: Widely available on the web, in every major browser since Sep 2015, and long enough to count on (since Mar 2018).

niso: Partial 55%. 123 of 221 subtests pass, by system: Linux 55%, macOS 55%. Engines: QuickJS, the engine niso's WPT run uses; Node and Porffor have no recorded run. WPT results recorded at f3b4fa8, 2026-11-10; web-features 3.45.0. WPT tests · niso's support · CSS, CSSConditionRule, CSSGroupingRule, CSSMediaRule

CSSStyleDeclaration is an interface in idl/html.webidl, exposed in Window. What it does is on MDN; this page says what niso has of it.

Status

The web features its members belong to, each with its Baseline status on the web and how much of the feature’s WPT suite passes in niso (see Web platform support).

Feature	On the web	In niso	Members
CSS object model	Widely available	Partial 55% 123 of 221 subtests pass	8

Members

cssText

attribute

attribute DOMString cssText;

int32_t niso_css_style_declaration_get_css_text(niso_dom* dom, niso_handle self, niso_str* out);
int32_t niso_css_style_declaration_set_css_text(niso_dom* dom, niso_handle self, const char* value, size_t value_len);

length

attribute

readonly attribute unsigned long length;

int32_t niso_css_style_declaration_get_length(niso_dom* dom, niso_handle self, uint32_t* out);

item()

operation

getter DOMString item(unsigned long index);

int32_t niso_css_style_declaration_item(niso_dom* dom, niso_handle self, uint32_t index, niso_str* out);

getPropertyValue()

operation

DOMString getPropertyValue(DOMString property);

int32_t niso_css_style_declaration_get_property_value(niso_dom* dom, niso_handle self, const char* property, size_t property_len, niso_str* out);

getPropertyPriority()

operation

DOMString getPropertyPriority(DOMString property);

int32_t niso_css_style_declaration_get_property_priority(niso_dom* dom, niso_handle self, const char* property, size_t property_len, niso_str* out);

setProperty()

operation

undefined setProperty(DOMString property, [LegacyNullToEmptyString] DOMString value, optional [LegacyNullToEmptyString] DOMString priority = "");

int32_t niso_css_style_declaration_set_property(niso_dom* dom, niso_handle self, const char* property, size_t property_len, const char* value, size_t value_len, const char* priority, size_t priority_len);

removeProperty()

operation

DOMString removeProperty(DOMString property);

int32_t niso_css_style_declaration_remove_property(niso_dom* dom, niso_handle self, const char* property, size_t property_len, niso_str* out);

supportedProperties()

static operation not in JS

[NisoInternal] static sequence<DOMString> supportedProperties();

int32_t niso_css_style_declaration_supported_properties(niso_dom* dom, niso_strs* out);

The CSS properties stylo supports, aliases included, for the glue’s camel-cased attributes.

Not in niso yet

Members the web has, by the BCD keys web-features 3.45.0 lists, that idl/ doesn’t declare. The list is partial: web-features lists only the keys it maps to a feature.

• @@iterator (CSS object model)
• parentRule (CSS object model)