Ways to retrieve the file name from the content-disposition header

Question

Ways to retrieve the file name from the content-disposition header

I received a file through an AJAX response. I am trying to extract the filename and file type from the content-disposition header in order to display a thumbnail for it. Despite conducting multiple searches, I have been unable to find a solution.

$(".download_btn").click(function () {
  var uiid = $(this).data("id2");

  $.ajax({
    url: "http://localhost:8080/prj/" + data + "/" + uiid + "/getfile",
    type: "GET",
    error: function (jqXHR, textStatus, errorThrown) {
      console.log(textStatus, errorThrown);
    },
    success: function (response, status, xhr) {
      var header = xhr.getResponseHeader('Content-Disposition');
      console.log(header);     
    }
});

Console output:

inline; filename=demo3.png

javascript ajax filenames file-type content-disposition

Answer 1

Answer №1

Back when I utilized it, here's how: Assuming the attachment is delivered as a server response.

I specified the response header in my REST service like this

response.setHeader("Content-Disposition", "attachment;filename=XYZ.csv");

function(response, status, xhr){
    var filename = "";
    var disposition = xhr.getResponseHeader('Content-Disposition');
    if (disposition && disposition.indexOf('attachment') !== -1) {
        var filenameRegex = /filename[^;=\n]*=((['"]).*?\2|[^;\n]*)/;
        var matches = filenameRegex.exec(disposition);
        if (matches != null && matches[1]) { 
          filename = matches[1].replace(/['"]/g, '');
        }
    }
}

UPDATE: Adapting the answer to fit your query- using inline instead of attachment

function(response, status, xhr){
    var filename = "";
    var disposition = xhr.getResponseHeader('Content-Disposition');
    if (disposition && disposition.indexOf('inline') !== -1) {
        var filenameRegex = /filename[^;=\n]*=((['"]).*?\2|[^;\n]*)/;
        var matches = filenameRegex.exec(disposition);
        if (matches != null && matches[1]) { 
          filename = matches[1].replace(/['"]/g, '');
        }
    }
}

Further information available here

Answer 2

Back when I utilized it, here's how: Assuming the attachment is delivered as a server response.

I specified the response header in my REST service like this

response.setHeader("Content-Disposition", "attachment;filename=XYZ.csv");

function(response, status, xhr){
    var filename = "";
    var disposition = xhr.getResponseHeader('Content-Disposition');
    if (disposition && disposition.indexOf('attachment') !== -1) {
        var filenameRegex = /filename[^;=\n]*=((['"]).*?\2|[^;\n]*)/;
        var matches = filenameRegex.exec(disposition);
        if (matches != null && matches[1]) { 
          filename = matches[1].replace(/['"]/g, '');
        }
    }
}

UPDATE: Adapting the answer to fit your query- using inline instead of attachment

function(response, status, xhr){
    var filename = "";
    var disposition = xhr.getResponseHeader('Content-Disposition');
    if (disposition && disposition.indexOf('inline') !== -1) {
        var filenameRegex = /filename[^;=\n]*=((['"]).*?\2|[^;\n]*)/;
        var matches = filenameRegex.exec(disposition);
        if (matches != null && matches[1]) { 
          filename = matches[1].replace(/['"]/g, '');
        }
    }
}

Further information available here

Answer 3

Answer №2

This response builds upon the earlier input by marjon4.

An even simpler method to achieve the desired outcome is by utilizing the split function in the following manner:

const fileName = xhr.getResponseHeader('content-disposition').split('filename=')[1].split(';')[0];

Please be aware that this approach might not yield the expected results if your file name contains a semi-colon (;).

Answer 4

This response builds upon the earlier input by marjon4.

An even simpler method to achieve the desired outcome is by utilizing the split function in the following manner:

const fileName = xhr.getResponseHeader('content-disposition').split('filename=')[1].split(';')[0];

Please be aware that this approach might not yield the expected results if your file name contains a semi-colon (;).

Answer 5

Answer №3

If you are looking to extract the filename while supporting both URL-encoded UTF-8 headers and ASCII headers, here is a method you can use:

public getFileName(disposition: string): string {
    const utf8FilenameRegex = /filename\*=UTF-8''([\w%\-\.]+)(?:; ?|$)/i;
    const asciiFilenameRegex = /^filename=(["']?)(.*?[^\\])\1(?:; ?|$)/i;

    let fileName: string = null;
    if (utf8FilenameRegex.test(disposition)) {
      fileName = decodeURIComponent(utf8FilenameRegex.exec(disposition)[1]);
    } else {
      const filenameStart = disposition.toLowerCase().indexOf('filename=');
      if (filenameStart >= 0) {
        const partialDisposition = disposition.slice(filenameStart);
        const matches = asciiFilenameRegex.exec(partialDisposition );
        if (matches != null && matches[2]) {
          fileName = matches[2];
        }
      }
    }
    return fileName;
}

Here are some important points to consider:

This method prioritizes the value of the UTF-8 filename over the ASCII name, if both are present.
When downloading a file, your browser may modify the filename further by replacing certain characters like " with _ (specifically in Chrome).
The ASCII pattern is most effective for quoted filenames but can also handle unquoted values. In the latter case, it considers all text after filename= up to either the next ; or the end of the header value as the filename.
Note that this method does not sanitize path information. If using this in a node app or similar context, ensure to cleanup the path info according to the operating system, leaving just the filename. Otherwise, a maliciously crafted filename could potentially overwrite critical system files.

Reference: MDN Content Disposition Header

Answer 6

If you are looking to extract the filename while supporting both URL-encoded UTF-8 headers and ASCII headers, here is a method you can use:

public getFileName(disposition: string): string {
    const utf8FilenameRegex = /filename\*=UTF-8''([\w%\-\.]+)(?:; ?|$)/i;
    const asciiFilenameRegex = /^filename=(["']?)(.*?[^\\])\1(?:; ?|$)/i;

    let fileName: string = null;
    if (utf8FilenameRegex.test(disposition)) {
      fileName = decodeURIComponent(utf8FilenameRegex.exec(disposition)[1]);
    } else {
      const filenameStart = disposition.toLowerCase().indexOf('filename=');
      if (filenameStart >= 0) {
        const partialDisposition = disposition.slice(filenameStart);
        const matches = asciiFilenameRegex.exec(partialDisposition );
        if (matches != null && matches[2]) {
          fileName = matches[2];
        }
      }
    }
    return fileName;
}

Here are some important points to consider:

This method prioritizes the value of the UTF-8 filename over the ASCII name, if both are present.
When downloading a file, your browser may modify the filename further by replacing certain characters like " with _ (specifically in Chrome).
The ASCII pattern is most effective for quoted filenames but can also handle unquoted values. In the latter case, it considers all text after filename= up to either the next ; or the end of the header value as the filename.
Note that this method does not sanitize path information. If using this in a node app or similar context, ensure to cleanup the path info according to the operating system, leaving just the filename. Otherwise, a maliciously crafted filename could potentially overwrite critical system files.

Reference: MDN Content Disposition Header

Answer 7

Answer №4

When looking at my specific scenario, the header had a structure like this:

attachment; filename="test-file3.txt"

As a result, I managed to retrieve the file name quite easily using a named group regular expression:

const regExpFilename = /filename="(?<filename>.*)"/;

const filename: string | null = regExpFilename.exec(contentDispositionHeader)?.groups?.filename ?? null;

Although there was a slight variation in the OP's case with the absence of quotation marks around the filename, I wanted to share my solution just in case others encounter a similar pattern.

Answer 8

When looking at my specific scenario, the header had a structure like this:

attachment; filename="test-file3.txt"

As a result, I managed to retrieve the file name quite easily using a named group regular expression:

const regExpFilename = /filename="(?<filename>.*)"/;

const filename: string | null = regExpFilename.exec(contentDispositionHeader)?.groups?.filename ?? null;

Although there was a slight variation in the OP's case with the absence of quotation marks around the filename, I wanted to share my solution just in case others encounter a similar pattern.

Answer 9

Answer №5

Perhaps you could simplify it to:

let downloadName = xhr.getResponseHeader('Content-Disposition').split("filename=")[1];

Answer 10

Perhaps you could simplify it to:

let downloadName = xhr.getResponseHeader('Content-Disposition').split("filename=")[1];

Answer 11

Answer №6

Here is a possible solution to the issue:

let responseHeaders = xhr.getResponseHeader('Response-Headers');
let start = responseHeaders.indexOf("file-name=") + 10; // Modify '+ 10' accordingly.
let end = responseHeaders.length - 1; // Verify if '- 1' is needed
let fileName = responseHeaders.substring(start, end);
console.log("File Name: " + fileName)

Answer 12

Here is a possible solution to the issue:

let responseHeaders = xhr.getResponseHeader('Response-Headers');
let start = responseHeaders.indexOf("file-name=") + 10; // Modify '+ 10' accordingly.
let end = responseHeaders.length - 1; // Verify if '- 1' is needed
let fileName = responseHeaders.substring(start, end);
console.log("File Name: " + fileName)

Answer 13

Answer №7

There is a library called content-disposition-attachment that can be utilized in web browsers:

npm install -D content-disposition-attachment

import { AxiosResponse } from "axios";
import { parse } from "content-disposition-attachment";

const getFilenameFromHeaders = ({ headers }: AxiosResponse<Blob>) => {
  const defaultName = "untitled";
  try {
    const { attachment, filename } = parse(headers["content-disposition"]);
    return attachment ? filename : defaultName;
  } catch (e) {
    console.error(e);
    return defaultName;
  }
};

Answer 14

There is a library called content-disposition-attachment that can be utilized in web browsers:

npm install -D content-disposition-attachment

import { AxiosResponse } from "axios";
import { parse } from "content-disposition-attachment";

const getFilenameFromHeaders = ({ headers }: AxiosResponse<Blob>) => {
  const defaultName = "untitled";
  try {
    const { attachment, filename } = parse(headers["content-disposition"]);
    return attachment ? filename : defaultName;
  } catch (e) {
    console.error(e);
    return defaultName;
  }
};

Answer 15

Answer №8

Hopefully this solution is useful!

const fileName = response.headers['content-disposition'].split('filename=')[1].split('.')[0];
const fileExtension = response.headers['content-disposition'].split('.')[1].split(';')[0];

Answer 16

Hopefully this solution is useful!

const fileName = response.headers['content-disposition'].split('filename=')[1].split('.')[0];
const fileExtension = response.headers['content-disposition'].split('.')[1].split(';')[0];

Answer 17

Answer №9

The following code snippet also handles cases where the filename contains unicode characters (e.g., -, !, (, ), etc.) and is encoded in utf-8 format like

filename*=utf-8''Na%C3%AFve%20file.txt

(refer to this link for more information). In such situations, the decodeURIComponent() function is employed to decode the filename.

const disposition = xhr.getResponseHeader('Content-Disposition');
filename = disposition.split(/;(.+)/)[1].split(/=(.+)/)[1]
if (filename.toLowerCase().startsWith("utf-8''"))
    filename = decodeURIComponent(filename.replace("utf-8''", ''))
else
    filename = filename.replace(/['"]/g, '')

If you are making a cross-origin request, remember to include

Access-Control-Expose-Headers: Content-Disposition

in the server-side response headers (see Access-Control-Expose-Headers) to expose the Content-Disposition header; otherwise, the filename will not be accessible on the client side via JavaScript. For example:

headers = {'Access-Control-Expose-Headers': 'Content-Disposition'}
return FileResponse("Naïve file.txt", filename="Naïve file.txt", headers=headers)

Answer 18

The following code snippet also handles cases where the filename contains unicode characters (e.g., -, !, (, ), etc.) and is encoded in utf-8 format like

filename*=utf-8''Na%C3%AFve%20file.txt

(refer to this link for more information). In such situations, the decodeURIComponent() function is employed to decode the filename.

const disposition = xhr.getResponseHeader('Content-Disposition');
filename = disposition.split(/;(.+)/)[1].split(/=(.+)/)[1]
if (filename.toLowerCase().startsWith("utf-8''"))
    filename = decodeURIComponent(filename.replace("utf-8''", ''))
else
    filename = filename.replace(/['"]/g, '')

If you are making a cross-origin request, remember to include

Access-Control-Expose-Headers: Content-Disposition

in the server-side response headers (see Access-Control-Expose-Headers) to expose the Content-Disposition header; otherwise, the filename will not be accessible on the client side via JavaScript. For example:

headers = {'Access-Control-Expose-Headers': 'Content-Disposition'}
return FileResponse("Naïve file.txt", filename="Naïve file.txt", headers=headers)

Answer 19

Answer №10

If you are not dealing with multipart body data, then this function comes in handy. It fetches the filename from the Content-Disposition header value (format: inline; filename=demo3.png) and decodes it as necessary.

const extractFileNameFromContentDisposition = disposition => { 
    if (disposition
        && (disposition.startsWith('attachment') || disposition.startsWith('inline'))
    ) {
        let filename = disposition.startsWith('attachment')
            ? disposition.replace("attachment;", "")
            : disposition.replace("inline;", ""); // replaces only first match
        filename = filename.trim();
        if (filename.includes("filename*=") && filename.includes("filename=")) {
            let filenames = filename.split(";"); // can parse by ";" because all ";"s inside filename are escaped
            if (filenames.length > 1) { // "filename=" or "filename*=" not found inside filename
                if (filenames[0].trim().startsWith("filename*=")) { // prefer "filename*="
                    filename = filenames[0].trim();
                } else {
                    filename = filenames[1].trim();
                }
            }
        }
        if (filename.startsWith("filename*=")) {
            filename = filename.replace("filename*=", "")
            .split("''").slice(1).join("''"); // remove encoding and ''
            filename = decodeURIComponent(filename);
        } else if (filename.startsWith("filename=")) {
            filename = filename.replace("filename=", "")
            if (filename.startsWith('"') && filename.endsWith('"')) {
                filename = filename.slice(1, filename.length - 1); // remove quotes
            }
        }
        return filename;
    }
}

The outcome of this function can be divided into name and extension like so:

let fullName = extractFileNameFromContentDisposition("inline; filename=demo.3.png").split(".");
let fileExtension = fullName[fullName.length - 1];
fullName = fullName.slice(0, fullName.length - 1).join(".");
console.log(fullName); // demo.3
console.log(fileExtension); // png

You can generate a thumbnail using SVG, for instance:

let colorPalette = {"png": "red", "jpg": "orange"};
// this is a basic example; feel free to create something more appealing
let createSVGThumbnail = extension => `<svg xmlns="http://www.w3.org/2000/svg" width="18" height="20" viewBox="0 0 18 20">
    <rect x="0" y="0" width="18" height="20" fill = "#FAFEFF"/>
    <rect x="0" y="7" width="18" height="6" stroke="${colorPalette[extension] || "blue"}" fill = "${colorPalette[extension] || "blue"}"/>
    <text stroke = "white" fill = "white" font-size = "6" x = "0" y = "12.5" textLength = "18">${extension.toUpperCase()}</text>
</svg>`;

...

// Utilize it as background-image for HTML element
let backgroundImage = "data:image/svg+xml;base64," + btoa(new TextDecoder().decode(createSVGThumbnail("png")));

Answer 20

If you are not dealing with multipart body data, then this function comes in handy. It fetches the filename from the Content-Disposition header value (format: inline; filename=demo3.png) and decodes it as necessary.

const extractFileNameFromContentDisposition = disposition => { 
    if (disposition
        && (disposition.startsWith('attachment') || disposition.startsWith('inline'))
    ) {
        let filename = disposition.startsWith('attachment')
            ? disposition.replace("attachment;", "")
            : disposition.replace("inline;", ""); // replaces only first match
        filename = filename.trim();
        if (filename.includes("filename*=") && filename.includes("filename=")) {
            let filenames = filename.split(";"); // can parse by ";" because all ";"s inside filename are escaped
            if (filenames.length > 1) { // "filename=" or "filename*=" not found inside filename
                if (filenames[0].trim().startsWith("filename*=")) { // prefer "filename*="
                    filename = filenames[0].trim();
                } else {
                    filename = filenames[1].trim();
                }
            }
        }
        if (filename.startsWith("filename*=")) {
            filename = filename.replace("filename*=", "")
            .split("''").slice(1).join("''"); // remove encoding and ''
            filename = decodeURIComponent(filename);
        } else if (filename.startsWith("filename=")) {
            filename = filename.replace("filename=", "")
            if (filename.startsWith('"') && filename.endsWith('"')) {
                filename = filename.slice(1, filename.length - 1); // remove quotes
            }
        }
        return filename;
    }
}

The outcome of this function can be divided into name and extension like so:

let fullName = extractFileNameFromContentDisposition("inline; filename=demo.3.png").split(".");
let fileExtension = fullName[fullName.length - 1];
fullName = fullName.slice(0, fullName.length - 1).join(".");
console.log(fullName); // demo.3
console.log(fileExtension); // png

You can generate a thumbnail using SVG, for instance:

let colorPalette = {"png": "red", "jpg": "orange"};
// this is a basic example; feel free to create something more appealing
let createSVGThumbnail = extension => `<svg xmlns="http://www.w3.org/2000/svg" width="18" height="20" viewBox="0 0 18 20">
    <rect x="0" y="0" width="18" height="20" fill = "#FAFEFF"/>
    <rect x="0" y="7" width="18" height="6" stroke="${colorPalette[extension] || "blue"}" fill = "${colorPalette[extension] || "blue"}"/>
    <text stroke = "white" fill = "white" font-size = "6" x = "0" y = "12.5" textLength = "18">${extension.toUpperCase()}</text>
</svg>`;

...

// Utilize it as background-image for HTML element
let backgroundImage = "data:image/svg+xml;base64," + btoa(new TextDecoder().decode(createSVGThumbnail("png")));

Ways to retrieve the file name from the content-disposition header

Answer №1

Answer №2

Answer №3

Answer №4

Answer №5

Answer №6

Answer №7

Answer №8

Answer №9

Answer №10

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