// @flow
import pixelsto from '../internalHelpers/_pxto'

/**
 * Convert pixel value to ems. The default base value is 16px, but can be changed by passing a
 * second argument to the function.
 * @function
 * @param {string|number} pxval
 * @param {string|number} [base='16px']
 * @example
 * // Styles as object usage
 * const styles = {
 *   'height': em('16px')
 * }
 *
 * // styled-components usage
 * const div = styled.div`
 *   height: ${em('16px')}
 * `
 *
 * // CSS in JS Output
 *
 * element {
 *   'height': '1em'
 * }
 */
const em: (value: string | number, base?: string | number) => string = pixelsto('em')
export default em