JavaScript - For loop with switch statement continually looping

Your loop will obviously still continue because you just only ended a case of every loop of i and will still test each value in the array of scenario[i].

How about using variable b as a handler that if an event like you run into a troll has been executed, then set b to a number greater than 0 then check if a value has been inserted into b before switching into the array again using if (b) break; where if b has a value greater than 0 then it will be set as true.

var scenario = new Array();
var b;
//simple function to create the number of scenarios
function Scenario() {
    howManyScenarios = function (number) {
        for (i = 0; i <= number; i++) {
            scenario[i] = ("Scenario " + (1 + i));
        };
    };

    howManyScenarios(4); //if you change the argument, add additional switch cases
    console.log(scenario[i]);
    //iterating through my howManyScenarios function to build out scenarios using a switch case
    createScenarios = function () {
        var ii = scenario.length;

        for (i = 0; i < ii; i++) {
            if (b) break;
            switch (scenario[i]) {
                case 'Scenario 1':
                    alert("You run into a troll");
                    b = 1;
                    break;
                case 'Scenario 2':
                    alert("You find a store to purchase goods from");
                    b = 2;
                    ItemShop();
                    break;
                case 'Scenario 3':
                    alert("You run into a ogre");
                    b = 3;
                    break;
                case 'Scenario 4':
                    alert("You run into a warewolf");
                    b = 4;
                    break;
                case 'Scenario 5':
                    alert("You run into a wizard");
                    b = 5;
                    return;
                    break;
            }; //close out switch cases
        }; //close out my for loop
    }; //close out createScenarios function 
    createScenarios();
}; //close out Scenario function

Scenario();

function ItemShop() {}

ANSWER 2 This one is one way on how we game developers make a functional game by using a series of object arrays, object classes and the like.

I remade your code into something easier to read, hope you learn something from this. :)

var numberofscenarios = 5;
var scenario = []; //array where scenarios will be
//this will be the accessible properties of scenario[] array
var _scenario = function(){
    this.name = ""; //name of scenario
    this.message =  "";
    this.doSomething = 0;
    this.status = 0 ;//1 = finished and 0 = false
};
var _event = function(mobname){
    this.mobname = mobname;
    this.battle = function(){//doSomething
                            console.log("Battle VS "+ this.mobname +" Start!");
                            };
    this.itemShop =  function(){//doSomething
        console.log(this.mobname + ": Welcome to the shop! How may I help you?");
                };
};

//generate the scenarios in the scenario[] array
function generateScenarios() {
    for (i = 0; i <= numberofscenarios; i++) {
            scenario[i] = new _scenario();
            scenario[i].name = i;

        switch (scenario[i].name) {
            case 1:
                scenario[i].message = "You run into a Troll";
                scenario[i].doSomething = new _event("Troll");      
                break;
            case 2:
                scenario[i].message = "You find a store to purchase goods from";
                scenario[i].doSomething = new _event("Shop Keeper");
            break;
            case 3:
                scenario[i].message = "You run into a Ogre";
                scenario[i].doSomething = new _event("Ogre");
                break;
            case 4:
                scenario[i].message = "You run into a Werewolf";
                scenario[i].doSomething = new _event("Werewolf");
                break;              
            case 5:
                scenario[i].message = "You run into a Wizard";
                scenario[i].doSomething = new _event("Wizard");
                break;
        }
    }
}
generateScenarios(); //generate the scenarios

//test the array of scenario class

//test the battle with Troll
console.log(scenario[1].message);
scenario[1].doSomething.battle();

//test the shop
console.log(scenario[2].message);
scenario[2].doSomething.itemShop();

//attempt to fight the Shopkeeper
console.log(scenario[2].message);
scenario[2].doSomething.battle();