We continue the coverage of some JavaScript libraries. We resume with the next library in the list mentioned. This is groupie. groupie provides semantics of a group where all functions are executed at once and a chain where they are executed in the declared order. The function registrations for group or chain is similar to the previous ones we have seen from the list.
The next library in the list is continuables which exposes the semantics that a unit continuables can be fulfilled. Consequently, many of the can be grouped or chained. What sets this library apart is the ease of use for node.js developers. For example:
Var async_fn = function(Val){
Var continuable = continuables.create();
Process.nextTick(function(){
Continuable.fulfill(Val);
});
Return continuable;
}
Now the continuables can be chained . If the chain ends with error it will be thrown. To prevent the continuable must return something. Therefore error and success cases can be differentiated based on the presence of return values and separate callbacks for these two states can be invoked via continuables.either
Slide exposes semantics similar to Async library and functions registered should not be throwing an error and instead pass it to the callback. The node.js has similar constructs in its low level but this library is puportedly easier. The convention introduces two kinds of functions. actors that take action, callbacks get results.callbacks handle all errors and is therefore the first argument. Callbacks can trap/call other callbacks. Actors pass a callback as the last argument. Actors must not throw and the return value is ignored. The library has a construct called asyncMap which is similar to the group functionality mentioned earlier. Essentially it waits for all the registered actors and callback to be complete. It also has a chain construct that enables one by one continuation.
Step is another library that enable parallel execution in addition and similar error handling.