base64转为ArrayBuffer

业务需求而找的函数
/ 仅仅在window下有效，因为用到了atob方法 /

    function Base64toArrayBuffer(base64Data) {
        const padding = '='.repeat((4 - base64Data.length % 4) % 4);
        const base64 = (base64Data + 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;
    }
    var  asd = 'ash55545jaf'
    console.log(Base64toArrayBuffer(asd))