Execute functions in array with parameters

Question

I want to iterate through an array of functions, passing each of them some parameters.

let board;
let hand;

const HandCheckers = [
    CheckForRoyalFlush(board, hand),
    CheckForStraightFlush(board, hand),
    CheckForQuads(board, hand),
    CheckForFullHouse(board, hand),
    CheckForFlush(board, hand),
    CheckForTrips(board, hand),
    CheckForPairs(board, hand),
    CheckForHighCard(board, hand),
];

for (let x = 0; x < HandCheckers.length; x ++) {
       HandCheckers[x](board, hand);
}

However, this code fails, giving me the following problem: ReferenceError: board is not defined

How can i call functions like this from an array with parameters?

Cheers!

Those function have already been called when you declared a HandCheckers array. The error tells exactly that - you're referring a variable that is not defined. — zerkms
– zerkms, Commented Jun 4, 2019 at 22:30
... and board and hand were not defined in either case. What exactly are you trying to achieve? — PM 77-1
– PM 77-1, Commented Jun 4, 2019 at 22:32
Instead of calling each one in your HandCheckers array (const HandCheckers = [ CheckForRoyalFlush(board, hand), CheckForStraightFlush(board, hand), ... ]; try just giving a reference, then you can call it in your for statement by passing in board and hand const HandCheckers = [ CheckForRoyalFlush, CheckForStraightFlush, ... ]; — jas7457
– jas7457, Commented Jun 4, 2019 at 22:34

bspates · Accepted Answer · 2019-06-04 22:34:28Z

4

Right now you are executing the functions when you declare them in the array. If you want to just store a function for later execution in the array, leave off the (). If you wanted the function to execute with the value of board and hand at the time it was placed in the array rather than when your iterating over the array use:

let HandCheckers = [
  CheckForRoyalFlush.bind(null, board, hand)
];
HandCheckers[0]();

answered Jun 4, 2019 at 22:34

bspates

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2 Comments

James Over a year ago

ah, but i will need to redefine the values of board and hand throughout my code, will this cater for that?

bspates Over a year ago

If you want to define the values later then its should be even simpler. `let HandCheckers = [ CheckForRoyalFlush ]; HandCheckers[0](board, hand);

Mark · Accepted Answer · 2019-06-04 22:46:19Z

1

If you want to iterate through an array of functions and pass in parameters, then only store the function reference. Then call them with parameters as you are doing:

let board;
let hand;

const HandCheckers = [
    CheckForRoyalFlush,
    CheckForStraightFlush,
    /* ... */
]

// or use `HandCheckers.forEach(f => f(board, hand))`
for (let x = 0; x < HandCheckers.length; x ++) {
       HandCheckers[x](board, hand);
}

answered Jun 4, 2019 at 22:46

Mark

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Comments

drclaw · Accepted Answer · 2019-06-05 00:37:30Z

0

Try this:

let board = 7;
let hand = 2;

const HandCheckers = [
    function CheckForRoyalFlush(board, hand){return board+hand},
    function CheckForStraightFlush(board, hand){return board*hand}
];

for (let x = 0; x < HandCheckers.length; x ++) {
    console.log(HandCheckers[x](board, hand));  
};

edited Jun 5, 2019 at 0:37

drclaw

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answered Jun 4, 2019 at 22:50

Paul

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