How to tell if a selection is on frame boundaries?

This is the use I had for the idea implemented:

This script takes a selection in pro tools, checks if the selection is on frame boundaries, and if not, extends the selection to the nearest frame boundaries before the selection start and after the selection end.

Comments and suggestions welcome! :)

function getSessionInfo() { // Gets sample rate, bit rate, frame rate

    if (!sf.ui.proTools.windows.whoseTitle.is('Session Setup').exists) { //opens session setup window
        sf.ui.proTools.menuClick({ menuPath: ["Setup", "Session"] });
    }

    let sessionSetupWin = sf.ui.proTools.windows.whoseTitle.is('Session Setup').first;

    let sessionInfo = { //stores sample rate as a number, sample rate as a string name, frame rate, and bit depth as an object called sessionInfo

        sampleRateName: sessionSetupWin.groups.whoseTitle.is('Session Format').first.children.whoseRole.is("AXStaticText").allItems[2].value.value,

        sampleRateNumber: (+(sessionSetupWin.groups.whoseTitle.is('Session Format').first.children.whoseRole.is("AXStaticText").allItems[2].value.value.split(" ")[0]) * 1000),

        bitRate: sf.ui.proTools.windows.whoseTitle.is('Session Setup').first.groups.whoseTitle.is('Session Format').first.popupButtons.allItems[1].value.value,

        frameRate: sf.ui.proTools.windows.whoseTitle.is('Session Setup').first.groups.whoseTitle.is('Session Format').first.popupButtons.allItems[2].value.value.split(" ")[0]



    };

    sessionSetupWin.windowClose();

    return sessionInfo;
}


function frameBoundaryCheck(sessionInfo, valueInSamples) { //uses math to check if a selected sample coincides with a frame boundary with the session's sample rate and frame rate

    let sampleRate = sessionInfo.sampleRateNumber;
    let frameRate = +(sessionInfo.frameRate);

    let frameRateNumerator = frameRate * 1000;
    let frameRateDenominator = 1000;

    if (Math.floor(frameRate) != frameRate) {

        frameRateNumerator = Math.ceil(frameRate) * 1000;
        frameRateDenominator = 1001;

    }

    let divisionFactor = (sampleRate / (frameRateNumerator / frameRateDenominator));
    let remainder = (valueInSamples % divisionFactor);
    let multiplier = (valueInSamples / divisionFactor);

    let leftEdge = Math.round(Math.floor(multiplier) * divisionFactor);
    let rightEdge = Math.round(Math.ceil(multiplier) * divisionFactor);

    let isFrameEdge = false;

    if (divisionFactor - remainder < 1) {
        isFrameEdge = true;

    } else if (remainder < 1) {

        isFrameEdge = true;

    }

    let result = {
        isFrameEdge: isFrameEdge,
        leftEdge: leftEdge,
        rightEdge: rightEdge,
    };

    return result;
}


////MAIN////

function main() {

    //Get the session info in Pro Tools
    sf.ui.proTools.appActivateMainWindow();
    let sessionInfo = getSessionInfo();

    //get the timeline selection in samples
    let timelineSelection = sf.ui.proTools.selectionGetInSamples();

    //check if the selection start is on a frame edge, and if not, extend the selection start to the closest frame edge before the selection
    let checkSelectionStart = frameBoundaryCheck(sessionInfo, timelineSelection.selectionStart);

    if (checkSelectionStart.isFrameEdge != true) {
        timelineSelection.selectionStart = checkSelectionStart.leftEdge;
    }

    //check if the selection end is on a frame edge, and if not, extend the selection end to the closest frame edge after the selection
    let checkSelectionEnd = frameBoundaryCheck(sessionInfo, timelineSelection.selectionEnd);

    if (checkSelectionEnd.isFrameEdge != true) {
        timelineSelection.selectionEnd = checkSelectionEnd.rightEdge;
    }

    //apply the new selection with the boundaries set to frame edges
    sf.ui.proTools.selectionSetInSamples({ selectionStart: timelineSelection.selectionStart, selectionEnd: timelineSelection.selectionEnd })
}

main();