Javascript Array of Functions

var array_of_functions = [
    first_function('a string'),
    second_function('a string'),
    third_function('a string'),
    forth_function('a string')
]

array_of_functions[0];

That does not work as intended because each function in the array is executed when the array is created.

What is the proper way of executing any function in the array by doing:

array_of_functions[0];  // or, array_of_functions[1] etc.

Thanks!

Answers:

Answer
var array_of_functions = [
    first_function,
    second_function,
    third_function,
    forth_function
]

and then when you want to execute a given function in the array:

array_of_functions[0]('a string');
Answer

I think this is what the original poster meant to accomplish:

var array_of_functions = [
    function() { first_function('a string') },
    function() { second_function('a string') },
    function() { third_function('a string') },
    function() { fourth_function('a string') }
]

for (i = 0; i < array_of_functions.length; i++) {
    array_of_functions[i]();
}

Hopefully this will help others (like me 20 minutes ago :-) looking for any hint about how to call JS functions in an array.

Answer

Without more detail of what you are trying to accomplish, we are kinda guessing. But you might be able to get away with using object notation to do something like this...

var myFuncs = {
  firstFunc: function(string) {
    // do something
  },

  secondFunc: function(string) {
    // do something
  },

  thirdFunc: function(string) {
    // do something
  }
}

and to call one of them...

myFuncs.firstFunc('a string')
Answer

Or just:

var myFuncs = {
  firstFun: function(string) {
    // do something
  },

  secondFunc: function(string) {
    // do something
  },

  thirdFunc: function(string) {
    // do something
  }
}
Answer

I would complement this thread by posting an easier way to execute various functions within an Array using the shift() Javascript method originally described here

  var a = function(){ console.log("this is function: a") }
  var b = function(){ console.log("this is function: b") }
  var c = function(){ console.log("this is function: c") }

  var foo = [a,b,c];

  while (foo.length){
     foo.shift().call();
  }
Answer

It's basically the same as Darin Dimitrov's but it shows how you could use it do dynamically create and store functions and arguments. I hope it's useful for you :)

var argsContainer = ['hello', 'you', 'there'];
var functionsContainer = [];

for (var i = 0; i < argsContainer.length; i++) {
var currentArg = argsContainer[i]; 

  functionsContainer.push(function(currentArg){
    console.log(currentArg);
  });
};

for (var i = 0; i < functionsContainer.length; i++) {
  functionsContainer[i](argsContainer[i]);
}

Answer

up above we saw some with iteration. Let's do the same thing using forEach:

var funcs = [function () {
        console.log(1)
  },
  function () {
        console.log(2)
  }
];

funcs.forEach(function (func) {
  func(); // outputs  1, then 2
});
//for (i = 0; i < funcs.length; i++) funcs[i]();
Answer

This is correct

var array_of_functions = {
            "all": function(flag) { 
                console.log(1+flag); 
              },
                "cic": function(flag) { 
                console.log(13+flag); 
              }                     
        };

array_of_functions.all(27);
array_of_functions.cic(7);
Answer

If you're doing something like trying to dynamically pass callbacks you could pass a single object as an argument. This gives you much greater control over which functions you want to you execute with any parameter.

function func_one(arg) {
    console.log(arg)
};

function func_two(arg) {
    console.log(arg+' make this different')
};

var obj = {
    callbacks: [func_one, func_two],
    params: ["something", "something else"];
};

function doSomething(obj) {
    var n = obj.counter
    for (n; n < (obj.callbacks.length - obj.len); n++) {
        obj.callbacks[n](obj.params[n]);
    }
};

obj.counter = 0;
obj.len = 0;
doSomething(obj); 

//something
//something else make this different

obj.counter = 1;
obj.len = 0;
doSomething(obj);

//something else make this different
Answer

Execution of many functions through an ES6 callback ????

const f = (funs) => {
  funs().forEach((fun) => fun)
}

f(() => [
  console.log(1),
  console.log(2),
  console.log(3)
])

Answer

Maybe it can helps to someone.

<!DOCTYPE html>
<html>
<head lang="en">
    <meta charset="UTF-8">
    <title></title>
    <script type="text/javascript">
        window.manager = {
            curHandler: 0,
            handlers  : []
        };

        manager.run = function (n) {
            this.handlers[this.curHandler](n);
        };

        manager.changeHandler = function (n) {
            if (n >= this.handlers.length || n < 0) {
                throw new Error('n must be from 0 to ' + (this.handlers.length - 1), n);
            }
            this.curHandler = n;
        };

        var a = function (n) {
            console.log("Handler a. Argument value is " + n);
        };

        var b = function (n) {
            console.log("Handler b. Argument value is " + n);
        };

        var c = function foo(n) {
            for (var i=0; i<n; i++) {
                console.log(i);
            }
        };

        manager.handlers.push(a);
        manager.handlers.push(b);
        manager.handlers.push(c);
    </script>
</head>
<body>
<input type="button" onclick="window.manager.run(2)" value="Run handler with parameter 2">
<input type="button" onclick="window.manager.run(4)" value="Run handler with parameter 4">
<p>
<div>
    <select name="featured" size="1" id="item1">
        <option value="0">First handler</option>
        <option value="1">Second handler</option>
        <option value="2">Third handler</option>
    </select>
    <input type="button" onclick="manager.changeHandler(document.getElementById('item1').value);" value="Change handler">
</div>
</p>
</body>
</html>
Answer

A short way to run 'em all:

[first_function, ..., nth_function].forEach (function(f) {
    f('a string');
}); 
Answer

the probleme of these array of function are not in the "array form" but in the way these functions are called... then... try this.. with a simple eval()...

array_of_function = ["fx1()","fx2()","fx3()",.."fxN()"]
var zzz=[];
for (var i=0; i<array_of_function.length; i++)
     { var zzz += eval( array_of_function[i] ); }

it work's here, where nothing upper was doing the job at home... hopes it will help

Answer

Using Function.prototype.bind()

var array_of_functions = [
        first_function.bind(null,'a string'),
        second_function.bind(null,'a string'),
        third_function.bind(null,'a string'),
        forth_function.bind(null,'a string')
    ]
Answer

I have many problems trying to solve this one... tried the obvious, but did not work. It just append an empty function somehow.

array_of_functions.push(function() { first_function('a string') });

I solved it by using an array of strings, and later with eval:

array_of_functions.push("first_function('a string')");

for (var Func of array_of_functions) {
   eval(Func);
   }
Answer

you got some top answers above. This is just another version of that.

var dictFun = {
     FunOne: function(string) {
     console.log("first function");
  },

   FuncTwo: function(string) {
   console.log("second function");
 },

  FuncThree: function(string) {
   console.log("third function");
}

}

Answer
/* PlanetGreeter */

class PlanetGreeter {
    hello   : { () : void; } [] = [];
    planet_1 : string = "World";
    planet_2 : string = "Mars";
    planet_3 : string = "Venus";
    planet_4 : string = "Uranus";
    planet_5 : string = "Pluto";
    constructor() {
        this.hello.push( () => { this.greet(this.planet_1); } );
        this.hello.push( () => { this.greet(this.planet_2); } );
        this.hello.push( () => { this.greet(this.planet_3); } );
        this.hello.push( () => { this.greet(this.planet_4); } );
        this.hello.push( () => { this.greet(this.planet_5); } );
    } 
    greet(a: string) : void { alert("Hello " + a); }
    greetRandomPlanet() : void { 
        this.hello [ Math.floor( 5 * Math.random() ) ] (); 
    } 
} 
new PlanetGreeter().greetRandomPlanet();
Answer

Ah man there are so many weird answers...

const execute = (fn) => fn()
const arrayOfFunctions = [fn1, fn2, fn3]

const results = arrayOfFunctions.map(execute)

or if you want to sequentially feed each functions result to the next:
compose(fn3, fn2, fn1)

compose is not supported by default, but there are libraries like ramda, lodash, or even redux which provide this tool

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