feat: use base64 encoding to speed up loading

Author: torfmaster

crates/cli-support/src/js/file_util.rs

@@ -0,0 +1,17 @@
+use base64::{prelude::BASE64_STANDARD_NO_PAD, Engine};
+
+pub(crate) fn create_load_inline_bytes_snippet(bytes: &[u8], variable_name: String) -> String {
+    format!(
+        "
+        let {variable_name};
+        const base64 = \"{base64}\";
+        if (typeof Buffer === 'undefined') {{
+            {variable_name} = Uint8Array.from(atob(base64), c => c.charCodeAt(0));
+        }} else {{
+            {variable_name} = Buffer.from(base64, 'base64');
+        }}
+        ",
+        variable_name = variable_name,
+        base64 = BASE64_STANDARD_NO_PAD.encode(&bytes),
+    )
+}

crates/cli-support/src/js/mod.rs

@@ -10,6 +10,7 @@ use crate::wit::{JsImport, JsImportName, NonstandardWitSection, WasmBindgenAux};
 use crate::{reset_indentation, Bindgen, EncodeInto, OutputMode, PLACEHOLDER_MODULE};
 use anyhow::{anyhow, bail, Context as _, Error};
 use binding::TsReference;
+use file_util::create_load_inline_bytes_snippet;
 use std::borrow::Cow;
 use std::collections::{BTreeMap, BTreeSet, HashMap, HashSet};
 use std::fmt;
@@ -19,6 +20,7 @@ use std::path::{Path, PathBuf};
 use walrus::{FunctionId, ImportId, MemoryId, Module, TableId, ValType};
 
 mod binding;
+pub(crate) mod file_util;
 
 pub struct Context<'a> {
     globals: String,
@@ -308,19 +310,14 @@ impl<'a> Context<'a> {
     fn generate_inline_wasm_loading(&mut self) -> String {
         let mut shim = String::new();
 
-        let buf = self.module.emit_wasm();
+        let wasm = self.module.emit_wasm();
+
+        let serialized = create_load_inline_bytes_snippet(&wasm, "bytes".into());
 
-        let mut serialized = "const bytes = new Uint8Array([".to_string();
-        let (last, bytes) = buf.split_last().unwrap();
-        for byte in bytes {
-            serialized.push_str(&format!("{},", byte));
-        }
-        serialized.push_str(&format!("{}", last));
-        serialized.push_str("]);");
         shim.push_str(&serialized);
         shim.push_str(
             "
-                const wasmModule = new WebAssembly.Module(bytes.buffer);
+                const wasmModule = new WebAssembly.Module(bytes);
                 const wasmInstance = new WebAssembly.Instance(wasmModule, imports);
                 wasm = wasmInstance.exports;
                 module.exports.__wasm = wasm;

crates/cli-support/src/wasm2es6js.rs

@@ -1,9 +1,10 @@
 use anyhow::{bail, Error};
-use base64::{prelude::BASE64_STANDARD, Engine as _};
 use std::collections::HashSet;
 use std::fmt::Write;
 use walrus::Module;
 
+use crate::js::file_util::create_load_inline_bytes_snippet;
+
 pub struct Config {
     base64: bool,
     fetch_path: Option<String>,
@@ -232,18 +233,7 @@ impl Output {
         let wasm = self.module.emit_wasm();
         let (bytes, booted) = if self.base64 {
             (
-                format!(
-                    "
-                    let bytes;
-                    const base64 = \"{base64}\";
-                    if (typeof Buffer === 'undefined') {{
-                        bytes = Uint8Array.from(atob(base64), c => c.charCodeAt(0));
-                    }} else {{
-                        bytes = Buffer.from(base64, 'base64');
-                    }}
-                    ",
-                    base64 = BASE64_STANDARD.encode(&wasm)
-                ),
+                create_load_inline_bytes_snippet(&wasm, "bytes".into()),
                 inst,
             )
         } else if let Some(ref path) = self.fetch_path {