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[ Passing argument to function prototype ]

This piece of code was provided as a working solution to a previous question on flow control:

// an object to maintain a list of functions that can be called in sequence
// and to manage a completion count for each one
function Sequencer() {
    this.list = [];
    this.cnt = 0;
}

Sequencer.prototype.add = function(/* list of function references here */) {
    this.list.push.apply(this.list, arguments);
}

Sequencer.prototype.next = function() {
    var fn = this.list.shift();
    if (fn) {
        fn(this);
    }
}

Sequencer.prototype.increment = function(n) {
    n = n || 1;
    this.cnt += n;
}

// when calling .decrement(), if the count gets to zero
// then the next function in the sequence will be called
Sequencer.prototype.decrement = function(n) {
    n = n || 1;
    this.cnt -= n;
    if (this.cnt <= 0) {
        this.cnt = 0;
        this.next();
    }
}

// your actual functions using the sequencer object
function test_1(seq, arg1, arg2, arg3) {
    seq.increment();
        // do something with  arg1, arg2 and arg3
    seq.decrement();
}

function test_2(seq) {
    seq.increment();
        // do something       
    seq.decrement();
}

function test_3(seq) {
    seq.increment();
        // do something       
    seq.decrement();
}

// code to run these in sequence
var s = new Sequencer();

// add all the functions to the sequencer
s.add(test_1, test_2, test_3);

// call the first one to initiate the process
s.next();

How can I pass arguments to test_1() when adding the function to s? For example (which obviously doesn't work):

s.add(test_1(10,'x',true), test_2);

Thanks

Answer 1


If the order was different, i.e. test_1(arg1, arg2, arg3, seq), you could use .bind:

s.add(test_1.bind(null, 10,'x',true) , test_2, test_3);

If you can't change the the order, pass an other function which in turn calls test_1:

s.add(function(seq) { test_1(seq, 10,'x',true); }, test_2, test_3);

Answer 2


You can access a function's given arguments with Function.arguments.