JavaScript 引入与交互 WebAssembly (Wasm) 完整指南

<script>
 /**
 * @param {String} path wasm 文件路径
 * @param {Object} imports 传递到 wasm 代码中的变量
 */
  function loadWebAssembly (path, imports = {}) {
   return fetch(path) // 加载文件
   .then(response => response.arrayBuffer()) // 转成 ArrayBuffer
   .then(buffer => WebAssembly.compile(buffer))
   .then(module => {
    imports.env = imports.env || {}
 
    // 开辟内存空间
    imports.env.memoryBase = imports.env.memoryBase || 0
    if (!imports.env.memory) {
    imports.env.memory = new WebAssembly.Memory({ initial: 256 })
    }
 
    // 创建变量映射表
    imports.env.tableBase = imports.env.tableBase || 0
    if (!imports.env.table) {
    // 在 MVP 版本中 element 只能是 "anyfunc"
    imports.env.table = new WebAssembly.Table({ initial: 0, element: 'anyfunc' })
    }
 
    // 创建 WebAssembly 实例
    return new WebAssembly.Instance(module, imports)
   })
  }
  //调用
  loadWebAssembly('test.wasm')
  .then(instance => {
  console.log(instance)
   const add = instance.exports._Z3addii//取出c里面的方法
   const square = instance.exports._Z6squarei//取出c里面的方法
 
   console.log('10 + 20 =', add(10, 20))
   console.log('3*3 =', square(3))
   console.log('(2 + 5)*2 =', square(add(2 + 5)))
  })
 
 </script>

cargo new --lib wasm-example
cd wasm-example

[lib]
crate-type = ["cdylib"]

[dependencies]
wasm-bindgen = "0.2"

use std::fs;
use wasm_bindgen::prelude::*;

#[wasm_bindgen]
pub fn read_folder(folder_path: &str) -> Result<Vec<String>, JsValue> {
    let entries = fs::read_dir(folder_path)
        .map_err(|err| JsValue::from_str(&format!("Error reading folder: {}", err)))?;

    let file_names: Vec<String> = entries
        .filter_map(|entry| {
            entry.ok().and_then(|e| e.file_name().into_string().ok())
        })
        .collect();

    Ok(file_names)
}

#[wasm_bindgen]
pub fn write_file(file_path: &str, content: &str) -> Result<(), JsValue> {
    fs::write(file_path, content)
        .map_err(|err| JsValue::from_str(&format!("Error writing file: {}", err)))?;

    Ok(())
}

wasm-pack build --target web --out-name wasm --out-dir ./static

<body>
<input type="file" id="folderInput" webkitdirectory directory multiple>
<ul id="fileList"></ul>

<input type="text" id="fileNameInput" placeholder="文件名">
<textarea id="fileContentInput" placeholder="文件内容"></textarea>
<button id="writeButton">写入文件</button>

<script>
    import init, {read_folder, write_file} from './static/wasm.js';

    async function run() {
        await init();

        const folderInput = document.getElementById('folderInput');
        const fileListElement = document.getElementById('fileList');

        folderInput.addEventListener('change', async (event) => {
            const files = event.target.files;
            fileListElement.innerHTML = '';

            for (let i = 0; i < files.length; i++) {
                const file = files[i];
                const listItem = document.createElement('li');
                listItem.textContent = file.name;
                fileListElement.appendChild(listItem);

                const fileContent = await readFile(file);
                console.log(fileContent);
            }
        });

        const writeButton = document.getElementById('writeButton');
        writeButton.addEventListener('click', async () => {
            const fileName = document.getElementById('fileNameInput').value;
            const fileContent = document.getElementById('fileContentInput').value;

            await writeFile(fileName, fileContent);
        });
    }

    function readFile(file) {
        return new Promise((resolve, reject) => {
            const reader = new FileReader();
            reader.onload = (e) => {
                resolve(e.target.result);
            };
            reader.onerror = (e) => {
                reject(e.target.error);
            };
            reader.readAsText(file);
        });
    }

    async function writeFile(fileName, fileContent) {
        try {
            await write_file(fileName, fileContent);
            console.log('File written successfully');
        } catch (error) {
            console.error('Error writing file:', error);
        }
    }

    run();
</script>
</body>

<body>
<a href="#" rel="external nofollow"  id="folderLink">选择文件夹</a>
<ul id="fileList"></ul>
<script>
    const folderLink = document.getElementById('folderLink');
    const fileListElement = document.getElementById('fileList');

    folderLink.addEventListener('click', (event) => {
        event.preventDefault();

        const folderInput = document.createElement('input');
        folderInput.type = 'file';
        folderInput.webkitdirectory = true;
        folderInput.directory = true;
        folderInput.multiple = true;

        folderInput.addEventListener('change', (event) => {
            const files = event.target.files;
            fileListElement.innerHTML = '';

            for (let i = 0; i < files.length; i++) {
                const file = files[i];
                const listItem = document.createElement('li');
                listItem.textContent = file.name;
                fileListElement.appendChild(listItem);
            }
        });

        folderInput.click();
    });
</script>
</body>