passing arguments AND a callback function

Question

I can write a simple function that uses a helper function to do work:

function calculate(a,b,fn){
    return fn(a,b);
}

function sum(args){
    total = 0;
    for (var i=0; i<arguments.length; i++){
        total += arguments[i];
        }
    return total;
}
console.log(calculate(15,8,sum));

As it's constructed now, the initial function will take 2 arguments and a function as its parameters. How do I configure it to accept ANY number of arguments plus a function? I tried:

function calculate(fn, args){
    args = [].slice.call(arguments, 1);
    return fn(args);
}

but in that scenario, invoking:

calculate(sum, 14, 5, 1, 3);

is the equivalent of invoking:

 sum([14, 5, 1, 3]);

What's the proper way of accomplishing this?

This might be of help - stackoverflow.com/questions/2141520/… — Jaanus Varus
– Jaanus Varus, Commented Jun 16, 2015 at 14:00

Ruan Mendes · Accepted Answer · 2015-06-16 14:55:55Z

3

Using Function.apply. It lets you pass an array and it turns each member of the array as each argument to the function being called.

function calculate(fn){
    var args = [].slice.call(arguments, 1);
    return fn.apply(this, args);
}

Another example, if you have an array and you want to find out the highest number in it.

function max(array) {
    // Math.max takes separate arguments, turn each member of the array 
    // into a separate argument
    return Math.max.apply(Math, array);
}

Or using calculate:

calculate(Math.max, 3, 2, 4, 7, 23, 3, 6); // 23

edited Jun 16, 2015 at 14:55

answered Jun 16, 2015 at 14:00

Ruan Mendes

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Comments

davguij · Accepted Answer · 2015-06-16 14:01:45Z

0

The easiest way I can think of is wrapping the arguments in an array or an object and iterating through it inside the function.

answered Jun 16, 2015 at 14:01

davguij

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