Sorting an array of functions in javascript

Question

I want to create a function that sorts a function and calls it. The problem is that each function may have a different number of arguments, and these arguments must be passed before the sorting. For example:

function sortFunciton(arrayOfFunctions) {

}

mySortedFunction = sortFunction([function1('a', 'b'), function2('a'), function3('a','b','c')])

The problem is that if I pass the array like this, I'll be passing the value of the function already, but I don't want these functions to be executed before the sorting, because they have heavy computation, so just one must be executed, which is why I'm sorting.

Isn't there a way to pass like this:

mySortedFunction = sortFunction([function1.args('a', 'b', 'c')], function2.args('a'), function3.args('a', 'b', 'c')])

and then do

mysortedFunction.callWithArgs()

?

You cannot compare functions, so I don't know how you would sort them? What exactly do you mean by "so just one must be executed, which is why I'm sorting"? — Bergi
– Bergi, Commented Jan 13, 2017 at 1:31

hackerrdave · Accepted Answer · 2017-01-13 01:36:08Z

1

You can pass the uninvoked function reference with certain bound arguments by using Function.prototype.bind:

function selectFunc(funcArray) {
  //some selection criteria
  return funcArray[0];
}

mySelectedFunc = selectFunc([function1.bind(null, 'a', 'b'), function2.bind(null, 'a'), function3.bind(null, 'a','b','c')]);

mySelectedFunc() //equivalent of running function1('a', 'b')

edited Jan 13, 2017 at 1:36

answered Jan 13, 2017 at 1:27

hackerrdave

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5 Comments

Gatonito Over a year ago

then I just call mySortedFunction()?

hackerrdave Over a year ago

following this pattern allows you to haven an array of functions, not an array of the results of the functions. what should sortFunction do?

Gatonito Over a year ago

It must select one of these functions to be invoked with these arguments.

hackerrdave Over a year ago

ah gotcha - so yea you could just call mySortedFunction() - will update answer

Thomas Over a year ago

@Gatonito, hackerrdave, binding this is fast as ****. Using bind() to partially apply a function (what you show) is way slower than a closure (in modern JS-engines). I'd recommend implementing the functions as higher order functions in the first place: instead of function fn1(arg1, arg2, a, b){ return a-b } and binding arg1 and arg2, function fn1(arg1, arg2){ return function(a, b){ return a-b} } and calling it as var sortFn = fn1("foo", "bar");

BrunoLM · Accepted Answer · 2017-01-13 01:29:55Z

0

You can use .bind then just call your function without arguments (it will be called with the parameters that have been bound)

function add(a, b) { return a + b; }
function mult(a, b) { return a * b; }
var functions = [add.bind(this, 1, 1), mult.bind(this, 5, 5)];

functions.forEach(f => console.log(f()));

answered Jan 13, 2017 at 1:29

BrunoLM

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Comments

Ghasan غسان · Accepted Answer · 2017-01-13 01:33:10Z

0

function sortFunciton(arrayOfFunctions) {

}

var mySortedFunction = sortFunction([
    { func: function1, arguments: ['a', 'b']}, 
    { func: function2, arguments: ['a']}, 
    { func: function3, arguments: ['a', 'b', 'c']}
]);

for (var i = 0; i < mySortedFunction.length; i++)
{
    mySortedFunction[i].func.apply(this, mySortedFunction[i].arguments);
};

answered Jan 13, 2017 at 1:33

Ghasan غسان

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