export function urlB64ToUint8Array ( base64String ) { const padding = '=' . repeat ( ( 4 - base64String . length % 4 ) % 4 ) ; const base64 = ( base64String + padding ) . replace ( /\-/g , '+' ) . replace ( /_/g , '/' ) ; const rawData = window . atob ( base64 ) ; const outputArray = new Uint8Array ( rawData . length ) ; for ( let i = 0 ; i < rawData . length ; ++ i ) { outputArray [ i ] = rawData . charCodeAt ( i ) ; } return outputArray ; }