如何在没有状态变量的情况下更新函数表达式？

Question

I'm creating a game in jquery and the player is created on click of a button. This is my function expression I use to hold it's info:

var getPlayerData = function() {
    return {
        name: $("#name").val(),//get name from input
        office_name: $("#office-name").val(), //get name from input
        score: parseInt($('#score').text(), 10), //players startwith 1k HC
        office_location: "office_loc1", //set Player's office
        office_multiplier: office_loc1, // Set Players office multiplier
        notified: false,
        projects_completed: 0
    };
};

Then I run this function within my other functions to access the player's variables, like so:

$('#create-player').click(function startProject() {
    getPlayerData();
});

I need a way to update both the office_location and office_multiplier variables using a conditional. The office multipliers are referencing this set of variables:

var office_loc1 = .01,
    office_loc2 = .02,
    office_loc3 = .03,
    office_loc4 = .04,
    office_loc5 = .05,

This is the conditional that I am trying to update some of those functions, here are the steps to the if conditional:

1. get score from html, check it it's > 0 &&
2. Check multipler is = office_loc1 variable &&
3. check if the player_notified = false

if (parseInt($('#score').text(), 10) > 0 && getPlayerData().office_multiplier === office_loc1 && getPlayerData().notified === false){ }

The key parts to pay attention to in the conditional are:

//upgrade players office and notify them
      getPlayerData().office_location = "office_loc2";
      getPlayerData().office_multiplier = office_loc2;
      getPlayerData().notified = true;

However, this will not actually update the variable. Does anyone have any ideas on this?

Thanks!

Answer 1

You are creating a new object instance of the player each time you call getPlayerData

If it is a read-only object, that wouldn't be a problem, but once you try to mutate any property of it, you will loose the updated value once you call getPlayerData() again.

You should keep the playerData as an instance variable, then you can access through your code.

var playerData = getPlayerData();

------------- edit -------------

Right after defining the getPlayerData function, you create a var playerData. Like this:

var getPlayerData = function() {
    return {
        name: $("#name").val(),//get name from input
        office_name: $("#office-name").val(), //get name from input
        score: parseInt($('#score').text(), 10), //players startwith 1k HC
        office_location: "office_loc1", //set Player's office
        office_multiplier: office_loc1, // Set Players office multiplier
        notified: false,
        projects_completed: 0
    };
};
var playerData = getPlayerData();

Then, on everyplace you would call getPlayerData() , you use playerData instead.

Answer 2

Part I

This code:

$('#create-player').click(function startProject() {
    getPlayerData();
});

is a bit suspicious. As per Flanagan, function can be invoked and it may not return any value, but if it does, then supposing that you want to store invocation result somewhere, just assign function invocation result to a variable.

var someVar = getPlayerData();

Otherwise the following happens:

• You invoke getPlayerData function
• The function returns an object
• The object is evaluated
• Because assignment operator is missing, the object is discarded

As if js would say: "I've executed the function, I see an object, but I don't see what I should do with it... let me just leave it as it is"

Part II. What would I suggest..

If you want to create an object, there's another way. At first glance I treated the following code as an object consructor:

var getPlayerData = function() {
    return {
        name: $("#name").val(),//get name from input
        office_name: $("#office-name").val(), //get name from input
        score: parseInt($('#score').text(), 10), //players startwith 1k HC
        office_location: "office_loc1", //set Player's office
        office_multiplier: office_loc1, // Set Players office multiplier
        notified: false,
        projects_completed: 0
    };
};

Instead of this, you could create an object with some functions that would update the fields you want to be updated. Let me demonstrate..

var PLAYER_DATA = function(name, office_name, score, office_location, office_multiplier, notified, projects_completed) {
    var nname = name,
        ooffice_name = office_name,
        sscore = parseInt(score, 10),
        ooffice_location = office_location,
        ooffice_multiplier = office_multiplier,
        nnotified = notified,
        pprojects_completed = projects_completed;

    function setName (name) {
        nname = name;
    }

    function getName() {
        return nname;
    }

    function setOfficeName(officeName) {
        ooffice_name = officeName;
    }

    function getOfficeName() {
        return ooffice_name;
    }

    function setScore(score) {
        sscore = parseInt(score, 10);
    }

    function getScore() {
        return sscore;
    }

    function setOfficeLocation(officeLocation) {
        ooffice_location = officeLocation;
    }

    function getOfficeLocation() {
        return ooffice_location;
    }

    function setOfficeMultiplier(officeMultiplier) {
        ooffice_multiplier = officeMultiplier;
    }

    function getOfficeMultiplier() {
        return ooffice_multiplier;
    }

    function setNotified(notified) {
        nnotified = notified;
    }

    function isNotified() {
        return nnotified;
    }

    function setProjectsCompleted(amount) {
        // is zero by default
        pprojects_completed = (amount > 0) ? amount : 0;
    }

    function getProjectsCompleted() {
        return pprojects_completed;
    }




    return {
        setName: setName,
        getName: getName,
        setOfficeName: setOfficeName,
        getOfficeName: getOfficeName,
        setScore: setScore,
        getScore: getScore,
        setOfficeLocation: setOfficeLocation,
        getOfficeLocation: getOfficeLocation,
        setOfficeMultiplier: setOfficeMultiplier,
        getOfficeMultiplier: getOfficeMultiplier,
        setNotified: setNotified,
        isNotified: isNotified,
        setProjectsCompleted: setProjectsCompleted,
        getProjectsCompleted: getProjectsCompleted
    }
};

After that you need to create this object passing some initial values as arguments to the conscructor:

var somePlayerData = new PLAYER_DATA($("#name").val(),
                                     $("#office-name").val(),
                                     // Notice that parseInt will be executed while creation of PLAYER_DATA 
                                     // object so there's no need to parse it again
                                     $('#score').text(),
                                     "office_loc1",
                                     "office_loc1",
                                     false,
                                     0)

After that you can access object's values via getters and set some values you want via setters