Feat/sandbox optimization

[CunjieLee]

在使用icestarkk开启沙箱接入子应用的时，我们发现在遇到执行的js代码需要频繁访问沙箱时，会遇到明显的性能问题和卡顿。
针对此问题，笔者想到了一种解决方法：
在使用时将常用的变量进行缓存，这样相关的变量就只会访问一次沙箱，之后代码执行时就不再需要再多次重复访问沙箱。

在后续学习中发现另一个微前端框架qiankun也在沙箱中默认开启使用类似的缓存方法来对沙箱性能进行优化，pr中的缓存的变量以及写法参考了qiankun。

下面是一个将icestark的sandbox核心代码简化后的例子：

// 简易沙箱
const sandbox = new Proxy(window, {
    get(target, prop, receiver) {
        if (prop === Symbol.unscopables) {
            return undefined;
        }
        console.log('访问了沙箱', prop)
        return target[prop]
    }
});

const start = performance.now();
const testScript = `
    // 执行的js代码，会频繁访问沙箱
    for (let i = 1; i <= 1000; i++) {
        const li = document.createElement('li');
        Math.abs(i)
        Math.random()
        new Array(3)
        let arr = new Array(3)
        Array.isArray(arr)
    }
        `;
const execScript = `with (sandbox) {;${testScript}\n}`;
const code = new Function('sandbox', execScript).bind(sandbox);
code(sandbox);
console.log('Time taken: ', performance.now() - start);

未进行缓存时候，以上代码中的Math等变量每执行一次都会访问沙箱造成不必要的性能开销，以上代码实际执行下来的时间大约在70ms。
如果简易沙箱开启缓存后，代码实际执行时间在0.8ms，性能差距非常明显。(图片在最后)
下面是简易沙箱开启缓存的示例代码：

const testScript = `
    // 下面是添加的缓存的代码
    const Math = sandbox.Math
    const Array = sandbox.Array
    const undefined = sandbox.undefined
    const Object = sandbox.Object
    const Promise = sandbox.Promise
    const setTimeout = sandbox.setTimeout
    const console = sandbox.console
    const document = sandbox.document
    // 执行的js代码，会频繁访问沙箱
    for (let i = 1; i <= 1000; i++) {
        const li = document.createElement('li');
        Math.abs(i)
        Math.random()
        new Array(3)
        let arr = new Array(3)
        Array.isArray(arr)
    }
        `;

在icestark沙箱中加上缓存后实际测试的效果：
测试示例代码未进行缓存前平均执行时间在54ms左右，开启缓存后的平均执行时间在19ms作用，速度提升了三倍左右
测试代码：

describe('sandbox: performance', () => {
  const testScript = `
    for (let i = 1; i <= 1000; i++) {
      const li = document.createElement('li');
      Math.abs(i);
      Math.random();
      new Array(3);
      let arr = new Array(3);
      Array.isArray(arr);
      Array.isArray([1,2,i]);
      new Date()
      requestAnimationFrame((i) => animate(i));
      JSON.stringify(i)
      new Map()
      const object1 = {
        a: "somestring",
        b: i,
        c: false,
      };
      Object.values(object1)
    }
  `;
  test('execution time', () => {

    // 测试沙盒执行时间
    const sandbox = new Sandbox();
    const sandboxStart = performance.now();
    sandbox.execScriptInSandbox(testScript);
    const sandboxTime = performance.now() - sandboxStart;
    console.log(`Sandbox execution time: ${sandboxTime.toFixed(2)}ms`);

    expect(sandboxTime).toBeGreaterThan(0);

    // 清理沙盒
    sandbox.clear();
  });
});

简易沙箱示例执行结果图片：

[Copilot]

Pull Request Overview

This PR introduces caching of global variables in the sandbox to reduce proxy overhead and improve script execution performance.

• Added constant.ts to define and filter a list of globals for caching.
• Prepended a destructuring statement in index.ts to cache these globals before executing the sandboxed script.

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
packages/sandbox/src/index.ts	Prepends destructured global variable declarations (cachedGlobals) before script execution.
packages/sandbox/src/constant.ts	Defines globalsInES2015 and composes the cachedGlobals array of properties to cache.

Comments suppressed due to low confidence (3)

packages/sandbox/src/index.ts:196

• [nitpick] The name scopedGlobalVariableDefinition is singular but contains multiple declarations. Consider renaming to scopedGlobalVariableDeclarations for clarity.

const scopedGlobalVariableDefinition = cachedGlobals.length ? `const {${cachedGlobals.join(',')}}=sandbox;` : '';

packages/sandbox/src/index.ts:195

• [nitpick] Add a unit test to verify that sandbox execution with cached globals yields the same behavior as without caching, ensuring functional correctness.

// Concatenate scopedGlobalVariables into variable declarations to cache global variables, avoiding proxy traversal on every use.

packages/sandbox/src/constant.ts:55

• Destructuring undefined as an identifier causes a syntax error since undefined is a reserved word. Remove it from cachedGlobals or cache it via a separate assignment (e.g., const undefinedVar = sandbox.undefined;).

'undefined',

[CunjieLee]

补充：已通过代码中全部sandbox测试用例