Get computed styles (in typescript)

getStyle.ts

// Gist adapted from: https://gist.github.com/cms/369133
export getStyle(el: Element, styleProp: string): string {
    let value;
    const defaultView = el.ownerDocument.defaultView;
    // W3C standard way:
    if (defaultView && defaultView.getComputedStyle) {
      // sanitize property name to css notation (hypen separated words eg. font-Size)
      styleProp = styleProp.replace(/([A-Z])/g, '-$1').toLowerCase();
      return defaultView.getComputedStyle(el, null).getPropertyValue(styleProp);
    } else if (el['currentStyle']) { // IE
      // sanitize property name to camelCase
      styleProp = styleProp.replace(/\-(\w)/g, function(str, letter) {
        return letter.toUpperCase();
      });
      value = el['currentStyle'][styleProp];
      return value;
    }

    return '';
  }

This code is very useful! Thanks!