[1, , 3].forEach(function(elt, idx) { console.log(idx + " is not omitted."); }); [1, , 3].forEach(function(elt, idx) { // $ Alert sum += elt; }); function f1(x, y) { // $ Alert return y; } f1(23, 42); function f2(x, y) { return y; } [].map(f2); function f3(x, y) { return y; } var g = f3; [].map(g); define(function (require, exports, module) { module.x = 23; }); // OK - starts with underscore function f(_p) { }