decode - helpers.ts - @hertzg/binstruct documentation

function decode



decode<T>(coder: Coder<T>,
buffer: Uint8Array,
context?: Context
): T

Decodes data using the provided coder, returning the decoded value.

This function decodes data from the provided buffer and returns only the decoded value, making it simple to use when you don't need to know how many bytes were consumed during decoding.

Examples

Basic decoding

import { assertEquals } from "@std/assert";
import { decode, struct, u16le, u8le } from "@hertzg/binstruct";

const coder = struct({ id: u16le(), flag: u8le() });
const buffer = new Uint8Array([42, 0, 7]); // Little-endian: id=42, flag=7

const decodedData = decode(coder, buffer);
assertEquals(decodedData.id, 42);
assertEquals(decodedData.flag, 7);

Processing multiple values from a buffer

import { assertEquals } from "@std/assert";
import { decode, encode, struct, u16le } from "@hertzg/binstruct";

const coder = struct({ value: u16le() });

// Create a buffer with multiple encoded values
const value1 = encode(coder, { value: 100 });
const value2 = encode(coder, { value: 200 });
const combinedBuffer = new Uint8Array(value1.length + value2.length);
combinedBuffer.set(value1, 0);
combinedBuffer.set(value2, value1.length);

// Decode first value
const decoded1 = decode(coder, combinedBuffer);
assertEquals(decoded1.value, 100);

// Decode second value from remaining buffer (need to know size)
const remaining = combinedBuffer.subarray(2); // Skip first 2 bytes
const decoded2 = decode(coder, remaining);
assertEquals(decoded2.value, 200);

Using custom context

import { assertEquals } from "@std/assert";
import { decode, createContext, struct, u32le } from "@hertzg/binstruct";

const coder = struct({ value: u32le() });
const buffer = new Uint8Array([42, 0, 0, 0]); // Little-endian: value=42
const context = createContext("decode");

const decodedData = decode(coder, buffer, context);
assertEquals(decodedData.value, 42);

Type Parameters

The type of data to decode

Parameters



coder: Coder<T>

The coder to use for decoding



buffer: Uint8Array

The buffer containing encoded data

optional



context: Context

Optional context for decoding (defaults to decode context)

Return Type

The decoded value