Convert JS Object to form data

Question

How can I can convert my JS Object to FormData?

The reason why I want to do this is, I have an object that I constructed out of the ~100 form field valu

Answer 1

The other answers were incomplete for me. I started from @Vladimir Novopashin answer and modified it. Here are the things, that I needed and bug I found:

• Support for file
• Support for array
• Bug: File inside complex object needs to be added with .prop instead of [prop]. For example, formData.append('photos[0][file]', file) didn't work on google chrome, while formData.append('photos[0].file', file) worked
• Ignore some properties in my object

The following code should work on IE11 and evergreen browsers.

function objectToFormData(obj, rootName, ignoreList) {
    var formData = new FormData();

    function appendFormData(data, root) {
        if (!ignore(root)) {
            root = root || '';
            if (data instanceof File) {
                formData.append(root, data);
            } else if (Array.isArray(data)) {
                for (var i = 0; i < data.length; i++) {
                    appendFormData(data[i], root + '[' + i + ']');
                }
            } else if (typeof data === 'object' && data) {
                for (var key in data) {
                    if (data.hasOwnProperty(key)) {
                        if (root === '') {
                            appendFormData(data[key], key);
                        } else {
                            appendFormData(data[key], root + '.' + key);
                        }
                    }
                }
            } else {
                if (data !== null && typeof data !== 'undefined') {
                    formData.append(root, data);
                }
            }
        }
    }

    function ignore(root){
        return Array.isArray(ignoreList)
            && ignoreList.some(function(x) { return x === root; });
    }

    appendFormData(obj, rootName);

    return formData;
}