Comments

單行註解 // 多行註解 /*...*/

Bad comments

好的程式碼不需要解釋註解或盡量減少，規則是如果一段程式碼必須要註解說明，他必須要被重寫。

// This code will do this thing (...) and that thing (...)
// ...and who knows what else...
very;
complex;
code;

function showPrimes(n) {
  nextPrime:
  for (let i = 2; i < n; i++) {

    // check if i is a prime number
    for (let j = 2; j < i; j++) {
      if (i % j == 0) continue nextPrime;
    }

    alert(i);
  }
}

// better
function showPrimes(n) {

  for (let i = 2; i < n; i++) {
    if (!isPrime(i)) continue;

    alert(i);
  }
}

function isPrime(n) {
  for (let i = 2; i < n; i++) {
    if (n % i == 0) return false;
  }

  return true;
}

// here we add whiskey
for(let i = 0; i < 10; i++) {
  let drop = getWhiskey();
  smell(drop);
  add(drop, glass);
}

// here we add juice
for(let t = 0; t < 3; t++) {
  let tomato = getTomato();
  examine(tomato);
  let juice = press(tomato);
  add(juice, glass);
}

// ...

// better
addWhiskey(glass);
addJuice(glass);

function addWhiskey(container) {
  for(let i = 0; i < 10; i++) {
    let drop = getWhiskey();
    //...
  }
}

function addJuice(container) {
  for(let t = 0; t < 3; t++) {
    let tomato = getTomato();
    //...
  }
}

Good comments

• 程式碼架構

• 函式的運用

• 為什麼使用這個方法

/**
 * Returns x raised to the n-th power.
 *
 * @param {number} x The number to raise.
 * @param {number} n The power, must be a natural number.
 * @return {number} x raised to the n-th power.
 */
function pow(x, n) {
  ...
}