converting imageAsset to base64 (nativescript-vue)

Question

want to convert the imageAsset to base64. sample code below, methods: {

    takePicture() {
        camera.takePicture({ width: 300, height: 300, keepAspectRatio: true, saveToGallery: false})
            .then(imageAsset => {

                this.pictureFromCamera = imageAsset;
                var image = new Image();
                image.src = imageAsset;
                console.log(imageAsset);