send POST with form using JSON data

form-post.js

function formPost(url, data, callback) {
    let form = $("<form>", {
        method: 'POST',
        action: url,
        target: "_blank"
    });

    function generateInput(iData, namePrefix) {
        if (namePrefix === undefined) namePrefix = "";
        for ([keyData, vData] of Object.entries(iData)) {
            let nameInput = keyData;
            if (namePrefix !== "") nameInput = `${namePrefix}[${keyData}]`

            if (typeof vData === "object") {
                if (vData.hasOwnProperty('length')) {
                    for ([idxData, aData] of Object.entries(vData)) {
                        if (typeof aData === 'object') {
                            generateInput(aData, `${nameInput}[${idxData}]`);
                        } else {
                            let inp = $("<input>", {
                                type: 'hidden',
                                name: nameInput,
                                value: vData
                            });

                            inp.appendTo(form);
                        }
                    }
                } else {
                    generateInput(vData, nameInput)
                }
            } else {
                let inp = $("<input>", {
                    type: 'hidden',
                    name: nameInput,
                    value: vData
                });

                inp.appendTo(form);
            }
        }
    }

    generateInput(data);
    form.appendTo($('body'));
    form.submit();
    form.remove();

    if (typeof callback === "function") {
        callback();
    }
}


// usage
formPost("https://domain.com/download/post", {
    query: "Hello",
    filter: {
        class_id: 10,
        unique: 1
    },
    order: [
        {dir: 'asc', column: 1}
    ]
}, function() {
    alert("Complete");
});