Salvar imagem em base64

handleCommit() {
        if (this.state.files.length === 0) {
            this.setState({
                openDlgImagesZero: true,
            });
            return false;
        }
        this.setState({ openSend: true });
        let link = "";
        let files = this.state.files.length;
        let idPropaganda = this.state.commit;
        let textInfo = this.state.textInfo;
        let ctx = this.context;
        if (this.state.files !== null) {
            let fileUploadRef = firebase.storage().ref();
            for (let i = 0; i < this.state.files.length; ++i) {
                let BASE64_MARKER = ';base64,';
                if (this.state.files[i].img.indexOf(BASE64_MARKER) === -1) {
                    let parts = this.state.files[i].img.split(',');
                    let contentType = parts[0].split(':')[1];
                    let raw = decodeURIComponent(parts[1]);
                    this.state.files[i].img = new Blob([raw], { type: contentType });
                } else {
                    let parts = this.state.files[i].img.split(BASE64_MARKER);
                    let contentType = parts[0].split(':')[1];
                    let raw = window.atob(parts[1]);
                    let rawLength = raw.length;
                    let uInt8Array = new Uint8Array(rawLength);
                    for (let i = 0; i < rawLength; ++i) {
                        uInt8Array[i] = raw.charCodeAt(i);
                    }
                    this.state.files[i].img = new Blob([uInt8Array], { type: contentType });
                }
                let thumb = this.state.filesThumb[i].img;
                let name = new Date().toISOString().slice(0, 19).replace('T', ' ') + "-" + [i] + ".jpg";
                let fileNameSave = Util.toHex(name);
                this.state.files[i].img.lastModifiedDate = new Date();
                let metadata = { contentType: 'image/jpeg' };
                let uploadTask = fileUploadRef.child('images/agencias/' + window._agencia + '/' + fileNameSave).put(this.state.files[i].img, metadata);
                uploadTask.on(firebase.storage.TaskEvent.STATE_CHANGED,
                    function (snapshot) {  }, function (error) {
                        switch (error.code) {
                            case 'storage/unauthorized':
                                //
                                break;
                            case 'storage/canceled':
                                //
                                break;
                            case 'storage/unknown':
                                //
                                break;
                        }
                    }, function () {
                        let downloadURL = uploadTask.snapshot.downloadURL;
                        DataPP._comitarPropaganda(idPropaganda, textInfo, downloadURL, thumb,
                            function (response) {
                                ctx.router.push('/propagandas?status=' + 4);
                            }.bind(this));
                    });
            }
        }
    }