关于JS你该知道的（错误）和不知道的（技巧）

你该知道的（容易犯的错误）

1. 忽略异步函数

// Incorrect: Ignoring the asynchronous nature of setTimeout
console.log("Start");
setTimeout(() => console.log("Timeout"), 0);
console.log("End");

// Correct: Understanding and handling asynchronous code
console.log("Start");
setTimeout(() => console.log("Timeout"), 0);
Promise.resolve().then(() => console.log("Promise"));
console.log("End");

2. 错误的作用域

// Incorrect: Variable declared without proper scoping
function incorrectScope() {
   
  for (var i = 0; i < 5; i++) {
   
    // 'i' is now global, not local to the loop
  }
  console.log(i); // Outputs 5
}

// Correct: Using 'let' for block-scoped variables
function correctScope() {
   
  for (let i = 0; i < 5; i++) {
   
    // 'i' is local to the loop block
  }
  // console.log(i); // Error: 'i' is not defined
}

3. 内存泄露

// Incorrect: Creating a memory leak with event listeners
function createMemoryLeak() {
   
  const element = document.getElementById("myElement");
  element.addEventListener("click", function handleClick() {
   
    // Some logic
  });
  // Forgot to remove the event listener
}

// Correct: Removing event listeners to avoid memory leaks
function avoidMemoryLeak() {
   
  const element = document.getElementById("myElement");
  function handleClick() {
   
    // Some logic
  }
  element.addEventListener("click", handleClick