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Understanding Fluent APIs in JavaScript
While designing Babylon.js v2.0 (a
library for building 3D on the web), I recently found myself wishing that more
APIs were fluent—that is, I wish the community could more easily read,
understand, and build upon the work while spending less time in the tech docs.
In this tutorial, I’ll walk through fluent APIs: what to consider, how to
write them, and cross-browser performance implications.
What's a Fluent API?
A fluent API, as stated by this Wikipedia article, is an implementation of
an object-oriented API that aims to provide for more readable code. JQuery is a great example of what a fluent API allows you to do:
$('<div></div>')
.html("Fluent API are cool!")
.addClass("header")
.appendTo("body");
The fluent API lets you chain
function calls by returning this object.
We can easily create a
fluent API like this:
var MyClass = function(a) {
this.a = a;
}
MyClass.prototype.foo = function(b) {
// Do some complex work
this.a += Math.cos(b);
return this;
}
As you can see, the trick
is just about returning the this
object (reference to current instance
in this case) to allow the chain to continue.
If you are not aware of
how the “this” keyword works in JavaScript, I recommend reading this great
article by Mike West.
We can then chain calls:
var obj = new MyClass(5);
obj.foo(1).foo(2).foo(3);
Before trying to do the
same with Babylon.js, I wanted to be sure that this would not generate some
performance issues.
What About Performance?
So I did a benchmark!
var count = 10000000;
var MyClass = function(a) {
this.a = a;
}
MyClass.prototype.foo = function(b) {
// Do some complex work
this.a += Math.cos(b);
return this;
}
MyClass.prototype.foo2 = function (b) {
// Do some complex work
this.a += Math.cos(b);
}
var start = new Date().getTime();
var obj = new MyClass(5);
obj.foo(1).foo(2).foo(3);
for (var index = 0; index < count; index++) {
obj.foo(1).foo(2).foo(3);
}
var end = new Date().getTime();
var start2 = new Date().getTime();
var obj2 = new MyClass(5);
for (var index = 0; index < count; index++) {
obj2.foo2(1);
obj2.foo2(2);
obj2.foo2(3);
}
var end2 = new Date().getTime();
var div = document.getElementById("results");
div.innerHTML += obj.a + ": With return this: " + (end - start) + "ms<BR>";
div.innerHTML += obj2.a + ": Without return this: " + (end2 - start2) + "ms";
As
you can see, foo
and foo2
do exactly the same thing. The only
difference is that foo
can be chained whereas foo2
cannot.
Obviously the call chain
is different between:
obj.foo(1).foo(2).foo(3);
and
obj2.foo2(1);
obj2.foo2(2);
obj2.foo2(3);
Given this code, I ran it
on Chrome, Firefox and IE to determine whether I have to get concerned about
performance.
And here are the results
I got:
- On Chrome, the regular API is 6% slower than the fluent API.
- On Firefox,
both APIs run at almost the same speed (the fluent API is 1% slower). - On IE,
both APIs run at almost the same speed (the fluent API is 2% slower).
The thing is that I added an operation into the function (Math.cos
) to
simulate some kind of treatment done by the function.
If I remove everything
and just keep the return
statement, on all browsers there is no
difference (actually just one or two milliseconds for 10,000,000 tries). You
can test this for yourself across the browsers. And if you don’t have the
devices handy, there are plenty of free tools on dev.modern.IE. Just don’t performance test a virtual machine
against a real device.
So my conclusion is: It’s
a go!
A fluent API is great—it produces more readable code, and you can use it without any problem or performance loss!
More Hands-On With
JavaScript
It might surprise you a bit, but Microsoft
has a bunch of free learning on many open-source JavaScript topics, and we’re on
a mission to create a lot more with Microsoft Edge coming. Check out my own:
- Introduction to WebGL 3D with HTML5 and
Babylon.JS - Building a Single Page Application with
ASP.NET and AngularJS - Cutting Edge Graphics in HTML
Or our team’s learning series:
Practical Performance Tips to Make your
HTML/JavaScript Faster (a seven-part series from responsive design to
casual games to performance optimization)
The Modern Web Platform Jump Start (the fundamentals of
HTML, CSS, and JavaScript)
Developing Universal Windows App with
HTML and JavaScript Jump Start (use the JS you’ve already created to
build an app)
And some free tools: Visual Studio Community, Azure Trial, and cross-browser testing tools for Mac, Linux, or
Windows.
This article is part of the web dev tech
series from Microsoft. We’re excited to share Microsoft Edge and the new EdgeHTML rendering engine with you. Get free
virtual machines or test remotely on your Mac, iOS, Android, or Windows device
@ https://dev.modern.ie/.
Original Link:
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