I'm trying to download the excel from flask using Ajax call. it's showing the response code as 200 but excel is not downloading and the error messages are as follows. 

Ajax Request :

$("#genExcel").on("click", function() {
 var xhttp = new XMLHttpRequest();

```
                // Data to post
                var dataarray = {};

                // Use XMLHttpRequest instead of Jquery $ajax

                xhttp.onreadystatechange = function() {
                    var a;
                    if (xhttp.readyState === 4 && xhttp.status === 200) {
                        // Trick for making downloadable link
                        a = document.createElement('a');
                        const objectURL = window.URL.createObjectURL(xhttp.response);
                        a.href = objectURL

                        //const objectURL = URL.createObjectURL(object)

                        // Give filename you wish to download
                        a.download = "test-file.xlsx";
                        a.style.display = 'none';
                        document.body.appendChild(a);
                        a.click();
                    }
                };
                // Post data to URL which handles post request
                xhttp.open("POST", '/genexcel');
                xhttp.setRequestHeader("Content-Type", "application/json");
                // You should set responseType as blob for binary responses
                //xhttp.responseType = 'blob';
                xhttp.send(JSON.stringify(dataarray));
            });

```

Flask function :

```
@app.route('/genexcel', methods=["GET", "POST"])
def createExcel():
    if request.method == 'POST':
        data = request.json  
        # process json data        
        return send_file(strIO, attachment_filename='test.xlsx',  as_attachment=True)

```

Errors :

1 [Report Only] Refused to evaluate a string as JavaScript because 'unsafe-eval' is not an allowed source of script in the following Content Security Policy directive: "script-src \* blob:".
==============================================================================================================================================================================================

2 Uncaught TypeError: Failed to execute 'createObjectURL' on 'URL': No function was found that matched the signature provided.
==============================================================================================================================

```
at XMLHttpRequest.xhttp.onreadystatechange

```

[![error and response](https://i.stack.imgur.com/I09BH.png)](https://i.stack.imgur.com/I09BH.png)