Improve performance

[magicode]

No description provided.

[sindresorhus]

This is intentional, for browser support.

[magicode]

this make new buffer it It takes performance.
Why an array of numbers is not good for checking?

[sindresorhus]

I appreciate the PR, but it's missing a benchmark proving the numbers you claim :)

[magicode]

try this

const fs = require('fs');
const filetype = require('.');

var file = fs.readFileSync(__dirname + "/fixture/fixture.png");

var time = 3000;
var starttime = Date.now();
var endtime = starttime + time;
var count = 0;
for(;Date.now()<endtime;count++){
    filetype(file);
}

console.log("%d ops/s" ,~~(count/((Date.now()-starttime)/1000)));

[sindresorhus]

@mifi Any thoughts on this?

[mifi]

It's a bit unclear why u compare with -1, why not use buf[1] !== undefined ?

[magicode]

It checks that it is also a number

[mifi]

Why is that needed? also '' > -1 is true which is obviously not a number

[magicode]

It's a check that on the way.
It's not important

[mifi]

I dunno if some of our users are sending in an array, but if they do, some file type checks will fail when removing the wrapping, like those using buf.subarray(), because array does not have this method.
Our docs however say clearly that we input should be Buffer or Uint8array. Still if we do this change i think we should bump major version.

Also, is it the removal of the wrapping or the length check that boosts performance?

[magicode]

What's important for performance.
It does not wrap if it Buffer or Uint8array.

[mifi]

Ok, I think then you can revert the buf[1] > -1 change, if it is not important for performance.
Also, don't assign const buf = input;, instead rename argument input to buf.
Then I think this can be merged if @sindresorhus agrees.

[sindresorhus]

Ok, sure, when @mifi's feedback is addressed.