CODEWITHSUNDEEP
javascriptnode.js
Bartosz Matuszewski
Bartosz Matuszewski

Reputation: 203

How to use Buffer.from to create Buffer view

I want to create view of part of a buffer, after checking in node.js documentation I found that method Buffer.from(arrayBuffer[, byteOffset[, length]]) should do exactly what I wanted. I started with the simple case but it already produces unexpected results so I'm definitely doing something wrong

var firstBuffer = Buffer.from('hello world');
var secondBuffer = Buffer.from(firstBuffer.buffer, 0, firstBuffer.length);

assert (firstBuffer.0 == secondBuffer.0) // fails

console.log (firstBuffer) // <Buffer 68 65 6c 6c 6f 20 77 6f 72 6c 64>
console.log (secondBuffer) // <Buffer da 07 00 00 da 07 00 00 db 07 00>

How to create buffer view?

Upvotes: 0

Views: 254

Answers (1)

Bartosz Matuszewski
Bartosz Matuszewski

Reputation: 203

It turns out that result of Buffer.from(string) can have offset property different than 0

Knowing that modified code works:

var firstBuffer = Buffer.from('hello world');
var secondBuffer = Buffer.from(firstBuffer.buffer, firstBuffer.offset, firstBuffer.length);


console.log (firstBuffer)  // <Buffer 68 65 6c 6c 6f 20 77 6f 72 6c 64>
console.log (secondBuffer) // <Buffer 68 65 6c 6c 6f 20 77 6f 72 6c 64>

assert (firstBuffer[0] == secondBuffer[0]) // pass

But it a shame that in official documentation there was no info about this "feature"

Upvotes: 0

Related Questions