base64转blob，blob转formData

1、base64转blob

function dataURItoBlob(base64Data) {
	var byteString;
	if (base64Data.split(',')[0].indexOf('base64') >= 0){
		byteString = atob(base64Data.split(',')[1]);
	}
	else{
		byteString = unescape(base64Data.split(',')[1]);
	}
	var mimeString = base64Data.split(',')[0].split(':')[1].split(';')[0];
	var ia = new Uint8Array(byteString.length);
	for (var i = 0; i < byteString.length; i++) {
		ia[i] = byteString.charCodeAt(i);
	}
	return new Blob([ia], {type:mimeString});
}

2、blob转formData

var blob = dataURItoBlob(newImgFile);
formData.append('headPic',blob, Date.now() + '.jpg');