laravel-jetstream/src/util/formData.js

<p align="center"><img src="https://laravel.com/assets/img/components/logo-jetstream.svg"></p>

export function objectToFormData(object, formData = new FormData(), parent = null) {
    if (object === null || object === 'undefined' || object.length === 0) {
        return formData.append(parent, object);
    }

    for (const property in object) {
        if (object.hasOwnProperty(property)) {
            appendToFormData(formData, getKey(parent, property), object[property]);
        }
    }

    return formData;
}

function getKey(parent, property) {
    return parent ? parent + '[' + property + ']' : property;
}

function appendToFormData(formData, key, value) {
    if (value instanceof Date) {
        return formData.append(key, value.toISOString());
    }

    if (value instanceof File) {
        return formData.append(key, value, value.name);
    }

    if (typeof value === "boolean") {
        return formData.append(key, value ? '1' : '0');
    }

    if (value === null) {
        return formData.append(key, '');
    }
    
    if (typeof value !== 'object') {
        return formData.append(key, value);
    }

    objectToFormData(value, formData, key);
}