Summary - Buffer
- Node.js course
- Intermediate
- Lesson 58/116
- 5 min
Combine Buffer.from, concat and toString to write a base64 converter.
Summary - Buffer
In this group you learned the core tools of buffers: creating a buffer from data with Buffer.from, joining with Buffer.concat, converting to string with toString and taking a portion with subarray.
You can combine these five tools to do a real task. For example, you can turn a string into a buffer, take a portion of it, append another buffer and print the result as text. This is a common pattern used in assembling stream data, joining file pieces or processing text. Now you will combine all pieces in one piece of code.
Practice Combine subarray and concat
Define const buf = Buffer.from("merhaba");. First print buf.subarray(0, 3).toString(). Then print Buffer.concat([buf, Buffer.from("!")]).toString() on a separate line.
Starter code
// Define a buffer with Buffer.from
// write here
// Take first three bytes with subarray, print with toString
// write here
// Append "!" with Buffer.concat, print with toString
// write hereSample solution
const buf = Buffer.from("merhaba");
console.log(buf.subarray(0, 3).toString());
console.log(Buffer.concat([buf, Buffer.from("!")]).toString());Expected output
mer merhaba!
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 Match each tool to its role
| Term | Meaning |
|---|---|
Buffer.from |
Creates a buffer from data |
Buffer.concat |
Joins buffers |
toString |
Converts to string |
subarray |
Returns a view |
2 Which method converts a buffer to a string?
buf.toString()- alloc
- toString Correct answer
- concat
- from
Explanation: toString converts a buffer to a string.
3 Complete the concat call
Buffer.____([buf, Buffer.from("!")])Buffer.concat([buf, Buffer.from("!")])Explanation: Buffer.concat joins an array of buffers.