Node.js stringDecoder.end() Method

The stringDecoder.end() method is used to return any remaining data stored in the decoder's internal buffer as a string. It ensures that incomplete multibyte characters are handled properly before the decoding process is completed.

Returns the remaining buffered data.
Handles incomplete UTF-8 and UTF-16 characters safely.
Can process an optional final buffer before ending.
Commonly used when decoding streams is complete.

Syntax

stringDecoder.end([buffer])

where,

buffer: It is a Buffer, TypedArray, or DataView that contains the bytes that have to be decoded. It is an optional parameter.

Return Value: It returns the remaining input stored in a buffer as a string.

Example 1:

JavaScript

// Import the string_decoder module
// and get the StringDecoder class 
// using object destructuring
const { StringDecoder } = require("string_decoder");

const decoder = new StringDecoder("utf-8");

// Using the end() method
const text_one = Buffer.from("GeeksforGeeks", "utf-8");
let decoded_text = decoder.end(text_one);
console.log("Decoded Text:", decoded_text);

// The Euro Symbol is denoted using
// the bytes [0xE2, 0x82, 0xAC]

console.log("Decoding the Euro Symbol:");

// Decoding the euro symbol
// Using the write() method to
// write the first two parts
console.log(decoder.write(Buffer.from([0xE2])));
console.log(decoder.write(Buffer.from([0x82])));

// Finishing the symbol using the end() method
// with that gives an additional call to write()
// using the last part of the buffer
console.log(decoder.end(Buffer.from([0xAC])));

Output:

Decoded Text: GeeksforGeeks
Decoding the Euro Symbol:
€

Example 2:

JavaScript

// Import the string_decoder module
// and get the StringDecoder class 
// using object destructuring
const { StringDecoder } = require("string_decoder");
const decoder = new StringDecoder("utf-8");
// The Cent Symbol is denoted using
// Buffer.from([0xc2, 0xa2])

// Decoding the complete cent symbol from buffer
let cent_symbol = Buffer.from([0xc2, 0xa2]);
let cent_symbol_out = decoder.end(cent_symbol);
console.log("Complete Cent Symbol:", cent_symbol_out);

// Decoding incomplete cent symbol using
// Buffer.write() method
cent_symbol = Buffer.from([0xc2]);
cent_symbol_out = decoder.write(cent_symbol);
console.log("Cent Symbol using write():",
                       cent_symbol_out);

// Decoding incomplete cent symbol
// using Buffer.end() method
cent_symbol = Buffer.from([0xc2]);
cent_symbol_out = decoder.end(cent_symbol);
console.log("Cent Symbol using end():",
                     cent_symbol_out);

Output:

Complete Cent Symbol: ¢
Cent Symbol using write():
Cent Symbol using end(): ??

Use cases of stringDecoder.end()

Flushing any remaining data from the decoder when a stream ends.
Handling incomplete multibyte characters at the end of encoded data.
Finalizing the decoding process after all chunks have been processed.
Preventing data loss when reading data in multiple buffer chunks.
Completing text extraction from network, file, or stream-based data sources.

Reference: https://nodejs.org/api/string_decoder.html#string_decoder_stringdecoder_end_buffer

Node.js stringDecoder.end() Method

Use cases of stringDecoder.end()

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