A long time ago, in 2011, I wrote my first DNI (Spanish ID) validation script. I did it with ActionScript.
Some years later, after the Flash era, I re-wrote it for Javascript.
Recently, I went into a heavily Functional Programming learning process and as a goal, I propose myself to create a new module applying what I learned.
The result (not following FP paradigm too much I would say) is:
Better DNI
singuerinc/better-dni_better-dni - The fastest Spanish DNI (NIE / NIF) validation_github.com
Quickly I found out that there are many modules doing the same…
Replicate what others already did is a little boring, so I changed my goal to
“Create the faster module to validate a DNI”
In this process, I found many ways to improve the speed of the code, although sometimes it looks a bit uglier, some of them made the code twice faster.
Note that you might get different results based on browser+cpu+etc. My findings are based basically on Chrome/Node. I would say that you should test your code in different environments and see where you can optimize.
Here is what I discovered:
str.substr() vs str.slice()
'0123456789'.slice(-9); // => '123456789''0123456789'.substr(-9); // => '123456789'
Winner: slice / x21 faster! / test
toLowerCase() vs toUpperCase()
I have to admit that I have never thought before why would one method be faster than the other. I was looking into the V8 code and looks like https://github.com/v8/v8/blob/master/src/string-case.cc#L16 is the answer to that.
'A'.toLowerCase(); // => 'a'
'a'.toUpperCase(); // => 'A'
This is especially useful if you need to compare two strings.
Before comparing them, better to convert them to lower case.
Winner: toLowerCase / slightly faster / test
Random image related to speed. You need one in all posts. Photo by James Traf on Unsplash
indexOf() vs object prop
const y = 'xyz'.indexOf('y'); // => 1
const y = {x: 0, y: 1, z: 2}['y'] // => 1
Winner: indexOf / slightly faster / test
String concatenation vs Template literals
I don’t know why I imagined that template literals were more complex than a simple string concatenation.
const x = 'x';
'yyy' + x;
`yyy${x}`; // faster
Winner: Template literals / slightly faster / test
Convert to number
parseInt('1234', 10); // => 1234
+'1234'; // => 1234
Winner: +sign / x6.12 faster! / test
Math.floor() vs Bitwise shift
I took some inspiration from this blog post.
Math.floor(1.123456789); // => 1
1.123456789 << 0; // => 1
Winner: Bitwise shift / slightly faster in jsperf but Math.floor() performs much better in my MacBook Pro. / test
Other tips that could help your code to run faster
Tip 1
Do easy validations first and return as quickly as possible. Take a look at these snippets:
if(someComplexValidation(value) && value.length !== 9) return;
vs
if(value.length !== 9 && someComplexValidation(value)) return;
It’s the same code right? Do the “easy” validation first so your code does not run and return if the first validation does not pass.
Tip 2
Avoid using costly methods like “toUpperCase()” and try to use smart alternatives:
const n = 'XYZ'.indexOf('y'.toUpperCase()); // => 2
vs
const n = 'XYZxyz'.indexOf('y') % 3; // => 2
Tip 3
If you know that you can achieve the same result with different methods, find the one that works better for each specific case:
const x1 = 'xyz'.substr(0, 1); // => 'x'
const x2 = 'xyz'[0]; // => 'x'
const x3 = 'xyz'.slice(0, 1); // => 'x'
I hope this would help you to optimize your code!
Do you want to contribute, make it faster? Open a pull request:
singuerinc/better-dni_better-dni - The fastest Spanish DNI (NIE / NIF) validation_github.com