Is it possible to call a variable by concatenating two strings in JavaScript?

Question

I'm trying to condense my code and I've looked at a number of articles on concatenating variables but I haven't been able to get anything to work the way I need it to.

Below are two snippets of code. They are functionally identical except the first snippet has variables that use 'Str' in their name and the second snippet uses 'Dex' instead. I plan on creating similar code with 'Int' and 'Ht' but I don't want to copy / paste and then go back to change the 'Str, Dex, Int, Ht' names all over my code over and over again.

Is it possible to put the 'Str, Dex, Int, Ht' into a variable [var1] (according to what button is pressed) and then use [var1] in place of 'Str, Dex, Int, Ht' so that the code only has to be written once?

//Define Stength Increase Function
var strIncrease = function () {
//Increase playerStrength by 1
    playerStr = playerStr + 1;
    playerStrDisplay.innerHTML = playerStr;
//Increase strengthCP by 10
    strCP = strCP + strCost;
    strCPDisplay.innerHTML = strCP;
//Decrease totalCP by 10
    totalCP = totalCP - strCost;
    totalCPDisplay.innerHTML = totalCP;
}

//Define Dexterity Increase Function
var dexIncrease = function () {
//Increase playerDexterity by 1
    playerDex = playerDex + 1;
    playerDexDisplay.innerHTML = playerDex;
//Increase DexterityCP by 20
    dexCP = dexCP + dexCost;
    dexCPDisplay.innerHTML = dexCP;
//Decrease totalCP by 20
    totalCP = totalCP - dexCost;
    totalCPDisplay.innerHTML = totalCP;
}

Yes: with a little bit of refactoring you should be able to leverage the fact that properties on objects are addressable via strings. var o = {}; o.foo = 'foo'; console.log(o['foo']); /* foo */ } — Ben Aston
– Ben Aston, Commented May 31, 2015 at 19:46
You should look into learning Object-oriented programming, especially if you're making games. — Oka
– Oka, Commented May 31, 2015 at 19:48

SLaks · Accepted Answer · 2015-05-31 20:00:33Z

3

You can use an object as a map:

var player = { str: 0, dex: 0, ... };

function increase(stat) {
    player[stat]++;
    document.getElementById(stat + 'Display').innerHTML = player[stat];
}

increate('str');

edited May 31, 2015 at 20:00

answered May 31, 2015 at 19:46

SLaks

891k182 gold badges1.9k silver badges2k bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Oka Over a year ago

What you call a map is just an object literal. Maps are something slightly different, and are part of the ES6 proposal.

Hauke S · Accepted Answer · 2015-06-01 06:08:48Z

0

You could define the attributes as properties of objects and access them using strings, like this:

var player = {
    str: 1,
    dex: 1,
    in: 1,
    ht: 1,
    strCP: 10,
    dexCP: 10,
    intCP: 10,
    htCP: 10,
    totalCP: 0
},
costs = {
   strCost: 10,
   dexCost: 10,
   inCost: 10,
   htCost: 10
};

function increaseAttribute(player, costs, attr) {
    player[attr] += 1;
    player[attr + "CP"] += costs[attr + "Cost"];
    player.totalCP += costs[attr + "Cost"];
.
.
}

function increaseStr () {
   increaseAttribute(player, costs, attr);
}
.
.
.

edited Jun 1, 2015 at 6:08

answered May 31, 2015 at 20:03

Hauke S

5555 silver badges10 bronze badges

1 Comment

Greg Wollf Over a year ago

Thank you for taking the time to write this example. It makes the most sense to my newbly programming mind.

Jerry · Accepted Answer · 2015-05-31 20:09:30Z

0

You can use closure to generate method dynamically.

For example.

var player = { 
   str : 0
   dex : 0
   int : 0
   ht : 0
}

function methodFactory (player, property, diff) {
    var mathod = function () {
        player[property] += diff;
    }
    return method;
}

then

var addInt = methodFactory (player, 'int', 1);
var addIntBy2 = methodFactory (player, 'int', 2);

addInt();

Write once, use everywhere

answered May 31, 2015 at 20:09

Jerry

1,0468 silver badges13 bronze badges

Collectives™ on Stack Overflow

Is it possible to call a variable by concatenating two strings in JavaScript?

3 Answers 3

1 Comment

1 Comment

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

1 Comment

1 Comment

Comments

Your Answer

Sign up or log in

Post as a guest

Related