addSymbolToAllArtboards.js

var doc = context.document
var page = doc.currentPage()
var pages = doc.pages()
var count = 0;
     
var navbarSymbol = findSymbolByName("Material/Bar/Nav");
     
for (i = 0; i < pages.count(); i++) {
    var artboards = pages[i].artboards()
     
    for (j = 0; j < artboards.count(); j++) {
        var appGroup = findLayerByName(artboards[j],"Application",MSLayerGroup);
         
        var artboardWidth = artboards[j].frame().width();
        var artboardHeight = artboards[j].frame().height();
     
        if (appGroup) {
            appGroup.setHasClickThrough(true);
     
            var navbarSymbolInstance = navbarSymbol.newSymbolInstance();
            appGroup.addLayers([navbarSymbolInstance]);
             
            navbarSymbolInstance.frame().setWidth(artboardWidth);
            navbarSymbolInstance.frame().setY(artboardHeight-navbarSymbol.frame().height());
     
            count++
        }
    }
}
     
doc.showMessage(count + ' Application layers were modified');
     
function findLayerByName(scope,layerName,type) {
    var scope = scope.layers();
     
    if (scope) {
        for (var i = 0; i < scope.count(); i++) {
            var name = scope.objectAtIndex(i).name().trim();
                 
            if ((!type && name == layerName) || (type && name == layerName && scope.objectAtIndex(i) instanceof type)) {
                return scope.objectAtIndex(i);
            }
        }
    }
     
    return false;
}
     
function findSymbolByName(symbolName) {
    var symbols = doc.documentData().allSymbols();
     
    for (var i = 0; i < symbols.count(); i++) {
        if (symbols.objectAtIndex(i).name() == symbolName) {
            return symbols.objectAtIndex(i);
        }
    }
     
    return false;
}