Javascript Array.prototype.filter() not working

Question

I have this piece of code running on the client that filters a list of events:

if (res)
{
    eventList.filter(function(event) {

        const out = res.fin         


        

Answer 1

Array.prototype.filter does not change array inplace, it returns new array made of items that satisfies the provided predicate. It should look like this

var result = eventList.filter(function(event) {
    return res.find(function(visibility) { return visibility.ID == event.id; }) === undefined;
});

You don't need to declare and assign variable and then return it from function, you can simply return expression