javascript闭包如何实现命令模式

function createCommand(operation, value) {
  return function(currentValue) {
    return operation(currentValue, value);
  };
}

function add(x, y) {
  return x + y;
}

function subtract(x, y) {
  return x - y;
}

// 创建加法和减法命令
const addFive = createCommand(add, 5);
const subtractTwo = createCommand(subtract, 2);

// 执行命令
console.log(addFive(10)); // 输出 15
console.log(subtractTwo(10)); // 输出 8

createCommand

operation

value

addFive

subtractTwo

function createTextEditor() {
  let text = "";
  const history = [];

  function setText(newText) {
    history.push(text);
    text = newText;
    console.log("Text updated:", text);
  }

  function undo() {
    if (history.length > 0) {
      text = history.pop();
      console.log("Undo:", text);
    } else {
      console.log("Nothing to undo.");
    }
  }

  return {
    setText: setText,
    undo: undo
  };
}

const editor = createTextEditor();
editor.setText("Hello");
editor.setText("Hello World");
editor.undo(); // 输出 "Hello"

setText

history

undo

history

null

let largeData = { /* 大量数据 */ };
const commands = [];

for (let i = 0; i < 1000; i++) {
  commands.push(function() {
    console.log(largeData.someProperty);
  });
}

// 循环结束后，解除对 largeData 的引用
largeData = null;

// 现在，如果 commands 中的闭包不再被使用，largeData 就可以被垃圾回收器回收。

for (let i = 0; i < 1000; i++) {
  (function(index) {
    commands.push(function() {
      console.log("Index:", index);
    });
  })(i);
}

index

commands

index