sequent

JavaScript async flow control

How to use

Wait (Join)

Execute after expected number of seq.done() are executed.

var Sequent = require('sequent');
var seq = new Sequent;

setTimeout(function(){
    seq.done("done 1"); // Arguments are optional
}, 500);

setTimeout(function(){
    seq.done("done 2", "end");
}, 1000);

// Wait for two seq.done()
seq.wait(2, function(arg1, arg2){
    // arg1 == "done 2", arg2 == "end"
    console.log("all done");
});

Break (as in for loops)

Exit waiting earlier than planned.

var Sequent = require('sequent');
var seq = new Sequent;

seq.wait(100, function(arg){
    // arg == "matured"
});

for (var i=0; i<100; i++) {
    if (i == 5) {
        // Break here and go to callback of wait()
        seq.mature("matured");
    }

    // seq.done() after seq.mature() are ignored
    seq.done("done " + i);
}

Queue (execute in order)

Execute functions in queued order when it becomes available.

var Sequent = require('sequent');
var seq = new Sequent;

var funcs = [];
var results = [];
for (var i=1; i<=10; i++) {
    // Functions will be executed in seq.queue()'d order.
    // seq.queue() returns a wrapped function.
    funcs.push(seq.queue(
        (function(_i){
            return function(){
                results.push(_i);
            }
        })(i)
    ));
}

funcs.reverse();

// Mark queued functions as available
for (var i=0, l=funcs.length; i<l; i++) {
    funcs[i]();
}

// Wait for all queued functions to be executed
seq.flush(function(){
    // results is [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
});

Installation

npm install sequent