JSON

A lightweight JSON wrapper for Go that optimizes WebAssembly binary size. It automatically switches between the standard encoding/json for backends and the browser's native JSON API (via syscall/js) for WASM builds.

Usage

package main

import (
    "github.com/tinywasm/json"
)

type User struct {
    Name    string `json:"name"`   // Included
    secret  string                  // Skipped (private)
    Ignored string `json:"-"`       // Skipped (tagged)
}

func main() {
    data := User{Name: "Alice", secret: "hidden", Ignored: "no"}

    // 1. Encode to *[]byte
    var jsonBytes []byte
    if err := json.Encode(data, &jsonBytes); err != nil {
        panic(err)
    }
    // Output: {"name":"Alice"}

    // 2. Decode from []byte
    var result User
    if err := json.Decode(jsonBytes, &result); err != nil {
        panic(err)
    }
}

API

The API is polymorphic and avoids unnecessary allocations by accepting various input/output types.

Encode(input any, output any) error

• input: The Go value to encode.
• output: The destination for the JSON output. Supported types:
  • *[]byte: Writes the JSON bytes to the slice.
  • *string: Writes the JSON string to the pointer.
  • io.Writer: Writes the JSON data to the writer (streaming).

Decode(input any, output any) error

• input: The source of the JSON data. Supported types:
  • []byte: Reads JSON from the byte slice.
  • string: Reads JSON from the string.
  • io.Reader: Reads JSON from the reader.
• output: A pointer to the Go value where the decoded data will be stored.

Benchmarks

Binary size comparison using TinyGo and Gzip compression:

Implementation	Binary Size (WASM + Gzip)
JSON	27.2 KB
encoding/json (stdlib)	119 KB

For build instructions and detailed benchmarking information, see benchmarks/README.md.

Screenshots

JSON (27.2 KB):

Standard Library JSON (119 KB):

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Contributing

License

See LICENSE for details.