CSSStyleDeclaration.getPropertyValue()
  The CSSStyleDeclaration.getPropertyValue() method interface returns a
  DOMString containing the value of a specified CSS property.
Syntax
var value = style.getPropertyValue(property);
Parameters
- 
    
propertyis aDOMStringrepresenting the property name (hyphen case) to be checked. 
Return value
- 
    
valueis aDOMStringcontaining the value of the property. If not set, returns the empty string. 
Example
  The following JavaScript code queries the value of the margin property in
  a CSS selector rule:
var declaration = document.styleSheets[0].cssRules[0].style;
var value = declaration.getPropertyValue('margin'); // "1px 2px"
Specifications
| Specification | 
|---|
| CSS Object Model (CSSOM)  # dom-cssstyledeclaration-getpropertyvalue  | 
Browser compatibility
BCD tables only load in the browser