If you want to fire the popup manually, set the timeout of the popup to be -1 (not zero) from the UI and use this call:
nitro.loadPrefillCaputure()
The popup can be toggled from the UI, however if you want to have events of the popup, you can set/define the following in the HEAD section of your page:
window.nitroSettings = {
"prefillCapture": {
"onClose": function () {},
"onShow": function () {},
"onFill": function (data) {
/* where data is seralized for that was there in the popup */
},
}
}