packages/fbjs/src/core/CSSCore.js
function(element, className) {
    invariant(
      !/\s/.test(className),
      'CSSCore.removeClass takes only a single class name. "%s" contains ' +
      'multiple classes.', className
    );

    if (className) {
      if (element.classList) {
        element.classList.remove(className);
      } else if (CSSCore.hasClass(element, className)) {
        element.className = element.className
          .replace(new RegExp('(^|\\s)' + className + '(?:\\s|$)', 'g'), '$1')
          .replace(/\s+/g, ' ') // multiple spaces to one
          .replace(/^\s*|\s*$/g, ''); // trim the ends
      }
    }
    return element;
  }
function(element, className) {
    invariant(
      !/\s/.test(className),
      'CSSCore.removeClass takes only a single class name. "%s" contains ' +
      'multiple classes.', className
    );

    if (className) {
      if (element.classList) {
        element.classList.remove(className);
      } else if (CSSCore.hasClass(element, className)) {
        element.className = element.className
          .replace(new RegExp('(^|\\s)' + className + '(?:\\s|$)', 'g'), '$1')
          .replace(/\s+/g, ' ') // multiple spaces to one
          .replace(/^\s*|\s*$/g, ''); // trim the ends
      }
    }
    return element;
  }
function ( element , className ) { invariant ( ! / \s / . test ( className ) , 'CSSCore.removeClass takes only a single class name. "%s" contains ' + 'multiple classes.' , className ) ; if ( className ) { if ( element . classList ) { element . classList . remove ( className ) ; } else if ( CSSCore . hasClass ( element , className ) ) { element . className = element . className . replace ( new RegExp ( '(^|\\s)' + className + '(?:\\s|$)' , 'g' ) , '$1' ) . replace ( / \s+ / g , ' ' ) // multiple spaces to one . replace ( / ^\s*|\s*$ / g , '' ) ; // trim the ends } } return element ; }
Removes the class passed in from the element

@param {DOMElement} element the element to set the class on
@param {string} className the CSS className
@return {DOMElement} the element passed in
Removes the class passed in from the element