Replacing if else if statements with something more efficient

I'm trying to learn coding by building a simple text game. The end game is going to have 4 rooms. You'll start in room 1, exit west to room 2, exit south to room 3, and finally exit east in room 4. (clockwise).

Anyway, my starting code is from a YouTube tutorial I found that consists of all if / else if statements. I already see that's terribly inefficient. My question is how do I improve this code?

I'm guessing I should make each room and it's contents an object (ie. Room 1 has a sword in it, so the object would contain the location of the room and the sword). I'm also guessing if I have a monster in a room, he'd be his own object.

My problem is if the above is correct (object) - I don't understand how to use the object once I create it. ie. if the user types "take sword" how do I call the object to do that?

If I'm on the complete wrong track, please point me back in the right direction.

Here's the current code for the first room:

$("form").submit(function() {
    var input = $("#commandLine").val();

    function check() {
        check = true;
    }

    if (input == "help") {
        $("#messageHelp").clone().insertBefore("#placeholder").fadeIn(1000);
        check();
    }

    if (input == "take sword" && currentRoom == "nCorridor") {
        $("<p>You picked up a sword.</p>").hide().insertBefore("#placeholder").fadeIn(1000);
        check();
    }
    else if (input == "take sword" && currentRoom != "nCorridor") {
        $("<p>The sword is not here.</p>").hide().insertBefore("#placeholder").fadeIn(1000);
        check();
    }
    else if (input != "take sword" && input != "help") {
        $("<p>I don't understand " + input +  ".</p>").hide().insertBefore("#placeholder").fadeIn(1000);
    }

    $("#commandLine").val("");
});

Ideally, I'd like to eliminate or greatly reduce my need to use if and else if statements for something more efficient.