skipping steps

[vpetrov]

Is it possible to implement conditional control flow? I would like to skip over a few steps.
Something along these lines:

step(
        function f1() { find('foo',this); },
        function f2(err,foo) { if (foo) f4(foo); else return null; },
        function f3(err) { create('foo',this); },
        function f4(err,foo) { print(foo); }
);

If not, what is the best way to implement the code above?

[xavi-]

Here's the easiest way I can think of:

step(
    function f1() { find('foo',this); },
    function f2(err,foo) {
        if (!foo) { // if there's no foo, create it
            create('foo', this)
        } else { // Otherwise this step is a no-op
            return foo; // Synchronously passed `foo` to the next step
        }
    },
    function f3(err,foo) { print(foo); }
);

That said, there's been some discussions on how to make this use case a bit more readable as well as some libraries that implement the ideas discussed:

• https://github.com/Nordberg/node-twostep (seems to be dead [maybe it's moved?], but at one point it had creationix's stamp of approval)
• https://github.com/xavi-/two-step (my own creation, so be kind :])

[ppbntl19]

Call a function outside of step to output final data..

ie,

step (
function one(){
if ( error or validaation error) )  return  response(res, req, error)
//code
},
function two(){
//code
}.
function three(){
//code
}
)
function response(res, req, error) {
//Code
}