Broken "Enable auto format on file save" feature for qml/js files

When selecting Tools>Options>Qt Quick>QML/JS Editing>Enable auto format on file save feature, some parts of codes in Javascript functions are removed after saving a changed file. For example if you have a function with more than one argument like:

function test(p1, p2) {
    console.log("Hello")
}

After saving the changes it changes in to:

function test(p1p2) {
    console.log("Hello")
}

Another example is this function :

function test() {
    for(var i=0;i<10;i++)
        console.log(i)
}

After saving it is changed to:

function test() {
    for (; i < 10; i++)
        console.log(i)
}

Also default values for function parameters are removed after saving.
For example this function :

function test(p = 1) {
    console.log("hello")
}

is changed to:

function test(p) {
    console.log("hello")
}

I didn't see these problems on Qt Creator 4.8.