Get histogram of current layer (not the whole's document) by javascript, CC 2017

Custom C++ plugin with scripting API would be best option.

michal-44680644

Are you going to get a histogram for layers with transparency?

If "yes", then the method will be more difficult. Using the selection does not give an accurate result.

//You can turn off all other layers then get the histogram then turn on all layers again

toggle_other_visible()
var hist = app.activeDocument.histogram;
//var hist = app.activeDocument.channels[0].histogram;
toggle_other_visible()
alert(hist)
function toggle_other_visible()
    {
    try {
        var desc = new ActionDescriptor();
        var list = new ActionList();
        var ref = new ActionReference();
        ref.putEnumerated( charIDToTypeID( "Lyr " ), charIDToTypeID( "Ordn" ), charIDToTypeID( "Trgt" ) );
        list.putReference( ref );
        desc.putList( charIDToTypeID( "null" ), list );
        desc.putBoolean( charIDToTypeID( "TglO" ), true );
        executeAction( charIDToTypeID( "Shw " ), desc, DialogModes.NO );
        }
    catch (e) { alert(e);} 
    }

I'm affraid you must make selection of layer you want to check its histogram.

Use this code where in the label of CLM function you have written in polish what it is for:

function CLM(v1, v2, v3) {// ZAZNACZENIE  KANAŁU / MASKI / WARSTWY Z PRZEZROCZYSTOŚCIĄ:
     function cTT(v) {return charIDToTypeID(v)} (ref1 = new ActionReference()).putProperty(c = cTT('Chnl'), cTT('fsel'));
     eval('(ref2 = new ActionReference())' + (v = (v1 && v2) ? '.putEnumerated(c, cTT(v1), cTT(v2))' : ''))
     if (v3) ref2.putName(cTT(v ? 'Lyr ' : 'Chnl'), v3); (dsc = new ActionDescriptor()).putReference(cTT('null'), ref1)
     dsc.putReference(cTT('T   '), ref2), executeAction(cTT('setd'), dsc, DialogModes.NO)
}
CLM('Chnl', 'Trsp'), hst = (aD = activeDocument).histogram, aD.selection.deselect()