3 ms·
You have to think about async code differently than you think about synchronous code. In PHP you might write: $data = getData(); And people want to substitu
by MatthewPhillips 15y ago
You have to think about async code differently than you think about synchronous code. In PHP you might write:
$data = getData();
And people want to substitute the return for a callback in js.
getData(function(data) {
// Do something with data.
});
That indeed does lead to callback mess. But when you are coding in js you rarely should use anonymous functions. I mostly just use them when I might want to perform recursion. Going back to my example, I would write the operation as an object like so:
var SomeObject = {
start: function() {
getData(dataGot);
},
dataGot: function(data) {
}
};
JavaScript is an object-oriented languages; use objects! They make async painless.
- tomp 15y ago> JavaScript is an object-oriented languages; use objects! They make async painless. In the example above, you're unable to use ''this'' in the ''dataGot'' function (when invoked as a callback). Object orientedness is very easy to get wrong in JavaScript, if you're coming from C++/Java/Python background.
- MatthewPhillips 15y agoRight, I excluded the bind for the sake of simplicity. I also forgot that it's this.dataGot. dataGot doesn't exist in that context :)
- bphogan 15y agoWrapping things in objects doesn't seem to help me. I'd still end up with this, thanks to callbacks. app.get('/documents', function(req, res) { Document.find().all(function(documents) { // 'documents' will contain all of the documents returned by the query res.send(documents.map(function(d) { // Return a useful representation of the object that res.send() can send as JSON return d.__doc; })); }); }); Seems to me that what's missing is something that lets me write it in a more simple way. What I have here looks like an absolute nightmare of coupling. So if you have some suggestions you could point me to that show a little more detail, I'd be really grateful.
- MatthewPhillips 15y agoI would create a DocumentRequest object that takes your req and res, then break apart your callbacks to separate functions on the DocumentRequest prototype. Then you would simply consume it with: app.get('/documents', new DocumentRequest);
- bphogan 15y agoThanks for this. Been thinking about this. Could you recommend a book on patterns like these?