How to loop through Buffers in Node.js?

Published September 27, 2020

To loop through a Buffer instance we can use the entries() method available in the buffer instance with the for...of looping statement.

Let's say we have a Buffer instance with String Hello World! like his,

// Buffer instance with string Hello World!
const buff = Buffer.from("Hello World!");

Now to loop through the Buffer let's use the entries() method and the for...of looping statement like this,

// Buffer instance with string Hello World!
const buff = Buffer.from("Hello World!");

// loop through buffer instance
for (let pair of buff.entries()) {
  console.log(pair);
}
  • The entries() method returns the data in [index, byte] format.

The output of the above code looks like this.

/*

[ 0, 72 ]
[ 1, 101 ]
[ 2, 108 ]
[ 3, 108 ]
[ 4, 111 ]
[ 5, 32 ]
[ 6, 87 ]
[ 7, 111 ]
[ 8, 114 ]
[ 9, 108 ]
[ 10, 100 ]
[ 11, 33 ]

*/

But if you don't want this in the [index, byte] format but as a single string, you can use the String.fromCharCode() method to get the appropriate character inside the loop like this,

// Buffer instance with string Hello World!
const buff = Buffer.from("Hello World!");

// loop through buffer instance
for (let pair of buff.entries()) {
  // get the byte of character
  const charCode = pair[1];
  // use String.fromCharCode() to get the appropriate character
  // for the byte
  console.log(String.fromCharCode(charCode));
}

The output of the above code looks like this,

/*

H
e
l
l
o

W
o
r
l
d
!

*/

See this example live in repl.it.

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