Redmine

function getInputParaId(input) {

    return `${input.name} ${input.value}`;

}

function replaceButKeepInput(targetId, newData) {

    if (!targetId)

        return;

    let element = document.getElementById(targetId);

    if (!element)

        return;

    let tmpElement = document.createElement("p");

    tmpElement.innerHTML = newData;

    let oldMap = new Map(

        Array.from(element.querySelectorAll("input"))

            .map(node => [getInputParaId(node), node.checked])

    )

    let newMap = new Map(

        Array.from(tmpElement.querySelectorAll("input"))

            .map(node => [getInputParaId(node), node.checked])

    )

    for (let input of element.querySelectorAll("input")) {

        if (newMap.get(getInputParaId(input)) === undefined) {

            // remember the checked state in a hidden input

            input.type = "hidden";

            // hidden input has to be additionally disabled to not get sent

            input.disabled = !input.checked;

            tmpElement.append(input);

        }

    }

    element.innerHTML = tmpElement.innerHTML;

    for (let input of element.querySelectorAll("input")) {

        if (oldMap.get(getInputParaId(input)))

            input.checked = true;

    }

}

          success: function(data){ replaceButKeepInput(targetId, data); },