var blob = new Blob([
        "--boundary_" + boundary + 'n'
        + "Content-Disposition: form-data; name="entity_content";" + "n"
        + "Content-Type: application/json" + "nn"
        + JSON.stringify(fields)
        + "nn"
        + "--boundary_" + boundary + "n"
        + "Content-Type: application/octet-stream" + "n"
        + "Content-Disposition: form-data; name="" + payloadField
        + ""; filename="" + filename + ""nn",
        payload,
        "nn"
        + "--boundary_" + boundary + "--"
    ], {type : 'multipart/form-data; boundary="boundary_' + boundary + '"'});

var blob = new Blob([
        "--boundary_" + boundary + 'n'
        + "Content-Disposition: form-data; name="entity_content";" + "n"
        + "Content-Type: application/json" + "nn"
        + JSON.stringify(fields)
        + "nn"
        + "--boundary_" + boundary + "n"
        + "Content-Type: application/octet-stream" + "n"
        + "Content-Disposition: form-data; name="" + payloadField
        + ""; filename="" + filename + ""nn",
        payload,
        "n"
        + "--boundary_" + boundary + "--"
    ], {type : 'multipart/form-data; boundary="boundary_' + boundary + '"'});