The CSSStyleDeclaration.setProperty() method interface sets a new value for a property on a CSS style declaration object.


style.setProperty(propertyName, value, priority);


  • propertyName is a DOMString representing the CSS property name (hyphen case) to be modified.
  • value Optional is a DOMString containing the new property value. If not specified, treated as the empty string.
    • Note: value must not contain "!important" -- that should be set using the priority parameter.
  • priority Optional is a DOMString allowing the "important" CSS priority to be set. If not specified, treated as the empty string. The following values are accepted:
    • String value "important"
    • Keyword undefined
    • String empty value ""

Return value


  • DOMException (NoModificationAllowedError): if the property or declaration block is read only.

JavaScript has a special simpler syntax for setting a CSS property on a style declaration object:

style.cssPropertyName = 'value';


The following JavaScript code sets a new value for the border-width CSS property on a selector rule:

var declaration = document.styleSheets[0].rules[0].style;
declaration.setProperty('border-width', '1px 2px');
// Equivalent to:
// declaration.borderWidth = '1px 2px';


Specification Status Comment
CSS Object Model (CSSOM)
The definition of 'CSSStyleDeclaration.setProperty()' in that specification.
Working Draft  
Document Object Model (DOM) Level 2 Style Specification
The definition of 'CSSStyleDeclaration' in that specification.

Browser compatibility

Update compatibility data on GitHub
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidEdge MobileFirefox for AndroidOpera for AndroidSafari on iOSSamsung Internet
Basic supportChrome Full support YesEdge Full support YesFirefox Full support YesIE Full support YesOpera Full support YesSafari Full support YesWebView Android Full support YesChrome Android Full support YesEdge Mobile Full support YesFirefox Android Full support YesOpera Android Full support YesSafari iOS Full support YesSamsung Internet Android ?


Full support  
Full support
Compatibility unknown  
Compatibility unknown

Document Tags and Contributors

Contributors to this page: connorshea, delete12345, determin1st, david_ross, Qantas94Heavy
Last updated by: connorshea,