add_coord_tracker.h

 
const char* add_coord_tracker = R"JS(
function add_coord_tracker(clsName){
 
    if (!clsName){
    clsName = 'TRACK_COORDS';
    }
    const BBOX_VARNAME='data-bbox';
 
    var elems = document.getElementsByClassName(clsName);
 
    for (var i=0; i<elems.length; ++i){
    var elem = elems.item(i);
    if (elem.hasAttribute(BBOX_VARNAME)){
        var bbox = elem.getAttribute(BBOX_VARNAME);
        
    }
    else {
        console.warn('element having class[', clsName, '] is missing attribute "' + BBOX_VARNAME, '"')
        console.note(elem)
    }
    }
}
)JS";