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THIS DOCUMENT IS IN PROGRESS. THIS PARAGRAPH SHALL BE REMOVED WHEN THIS DOCUMENT IS DONE.
TO DO:
- Remove benchmark from readme
# Koa vs Express
## Does Koa replace Express?
It's more like Connect, but a lot of the Express goodies
were moved to the middleware level in Koa to help form
a stronger foundation. This makes middleware more enjoyable
and less error-prone to write, for the entire stack, not
just the end application code.
Typically many middleware would
re-implement similar features, or even worse incorrectly implement them,
when features like signed cookie secrets among others are typically application-specific,
not middleware specific.
## Does Koa replace Connect?
No, just a different take on similar functionality
now that generators allow us to write code with less
callbacks. Connect is equally capable, and some may still prefer it,
it's up to what you prefer.
## Why isn't Koa just Express 4.0?
Koa is a pretty large departure from what people know about Express,
the design is fundamentally much different, so the migration from
Express 3.0 to this Express 4.0 would effectively mean rewriting
the entire application, so we thought it would be more appropriate
to create a new library.
## Is Koa faster than Express?
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Koa and Express have very similar benchmark results, both of which are more than enough for most applications. This is especially true for applications with high traffic running multiple instances, because you are scaling horizontally right?
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The following results were produced on a Retina Macbook Pro, showing only the cost of running noop middleware.
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```
1 middleware
8849.36
5 middleware
8685.74
10 middleware
8511.08
15 middleware
8456.86
20 middleware
8211.93
30 middleware
8102.98
50 middleware
7617.67
100 middleware
6899.45
```
Here are the benchmarks for Express:
```
1 middleware
7805.19
5 middleware
7707.15
10 middleware
7475.08
15 middleware
7261.73
20 middleware
7012.07
30 middleware
6672.76
50 middleware
6255.92
100 middleware
5000.98
```
## How is Koa different than Connect/Express?
### Generated-based control flow
Thanks to co.
No callback hell.
Better error handling through try/catch.
No need for domains.
### Koa is barebone
Unlike both Connect and Express, Koa does not include any middleware.
Unlike Express, routing is not provided.
Unlike Express, many convenience utilities are not provided. For example, sending files.
More modular.
### Koa relies less middleware
For example, instead of a "body parsing" middleware, you would instead use a body parsing function.
### Koa abstracts node's request/response
Less hackery.
Proper stream handling.
