src/dom/getClassIndex.js
function getClassIndex(element, className) {
  assertType(element, Node, false, 'Invalid element specified');
  assertType(className, 'string', false, `Invalid class name: ${className}`);
  let classList = element.className.split(' ');
  return classList.indexOf(className);
}
function getClassIndex(element, className) {
  assertType(element, Node, false, 'Invalid element specified');
  assertType(className, 'string', false, `Invalid class name: ${className}`);
  let classList = element.className.split(' ');
  return classList.indexOf(className);
}
function getClassIndex ( element , className ) { assertType ( element , Node , false , 'Invalid element specified' ) ; assertType ( className , 'string' , false , ` ${ className } ` ) ; let classList = element . className . split ( ' ' ) ; return classList . indexOf ( className ) ; }
Gets the index of a specified class in a DOM element,

@param {Node} element - Target element.
@param {string} className - Target class name.

@return {number} Index of given class name. -1 if not found.

@alias module:requiem~dom.getClassIndex
Gets the index of a specified class in a DOM element