How can i get data from FormData in javascript?

Question

I need to read data from FormData? I try to read something like someFormatData["valueName"] but it not working. options["fileId"] or options["file"] does not work. Also I try options.fileId same result:

function upload(file, fileId, callback) {
    var formData = new FormData();
    formData.append("file", file);
    formData.append("fileID", fileId);

    $.ajax({
        url: '/url',
        type: 'POST',
        data: formData,
        processData: false,
        contentType: false,
        success: function(response) {
            callback(response);
        }
    });
}


asyncTest("test upload chunk", function() {
    var blob = new Blob(["Hello world!"], { type: "text/plain" }),        
        options = null,
        fileID ="someFileID",
        response;

    jQuery.ajax = function(param) {
        options = param;   // THIS is FormData object 
        // how to read fileId and file from here
    };

    upload(blob, fileID, function (data) {
        response = data;  
    });

    options.success({
        someProp: 'responseFromServer'
    });

    setTimeout(function() {
        QUnit.equal(options, "dataTosend", "parameters is OK");
        QUnit.equal(response["someProp"], "responseFromServer", "Response ok");
        start();
    },1000);
});

Is param the FormData object, or param.data ? From the doc at developer.mozilla.org/en-US/docs/DOM/XMLHttpRequest/FormData, I don't think there is a way to access the data. However, unless you're testing $.ajax, you might want to spy on FormData to check that you called append with the right ids... — phtrivier
– phtrivier, Commented Feb 14, 2013 at 14:30

Mike · Accepted Answer · 2020-04-18 11:31:25Z

6

If you take your FormData object you can use a few different methods on it… What you are looking for is

formData.get()

or

formData.getAll()

https://developer.mozilla.org/en-US/docs/Web/API/FormData

Note that the get() method is not fully supported on all browsers.

edited Apr 18, 2020 at 11:31

Mike

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answered Jun 1, 2015 at 4:34

Kris Boyd

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4 Comments

Kris Boyd Over a year ago

Thanks @MarcinNabialek been a long day and forgot the markup!

Kris Boyd Over a year ago

get() does not, getAll() is supported by Chrome developer.mozilla.org/en-US/docs/Web/API/FormData/…

Eugene Over a year ago

Yes, I saw it on that page, but both methods aren't work in my Chrome (v40)

user5260143 Over a year ago

see at developer.mozilla.org/en-US/docs/Web/API/FormData/get. it says that chrome, IE and safari dont support those methods.

Koushik Das · Accepted Answer · 2021-10-16 07:05:18Z

0

You can read using this

formData.get('fileId') // to read Id
formData.get('file') // to read the file

answered Oct 16, 2021 at 7:05

Koushik Das

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Comments

Daweb · Accepted Answer · 2022-06-21 08:22:31Z

0

Another way to list all entries of a FormData :

for(const entry of formData){
  console.log(entry); // Array: ['entryName', 'entryValue']
}

answered Jun 21, 2022 at 8:22

Daweb

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