是'for'循环所以内存饥饿，与es6中的'for'相比？

Question

在Javascript中，是循环，所以内存密集吗？我得到一个内存问题，它应该只循环36次：

const suits = ['♥', '♠', '♣', '♦'],
      ranks = [6, 7, 8, 9, 10, 'J', 'Q', 'K', 'A'];
var cards = [];
for (let i = 0; i < suits.length; i++) {
  for (let j = 0; j < ranks.length; i++) {
    var colour = 'black';
    if (suits[i] === '&hearts;' || suits[i] === '&diam;') {
      colour = 'red';
    }
    cards.push({
      suit : suits[i],
      rank : ranks[j],
      colour : colour,
      value : j+1
    });              
  }
}
console.log(cards);

https://jsfiddle.net/xntL1ygj/

但这很好：

const suits = ['♥', '♠', '♣', '♦'],
      ranks = [6, 7, 8, 9, 10, 'J', 'Q', 'K', 'A'];

let cards = [];

for (let suit of suits) {
  for (let rank of ranks) {
    var colour = 'black';
    if (suit === '♥' || suit === '⋄') {
      colour = 'red';
    }  
    cards.push({
      suit : suit,
      rank : rank,
      colour : colour,
      //value : j+1
    });              
  }
}
console.log(cards);

https://jsfiddle.net/zfktu35t/

Answer 1

const suits = ['♥', '♠', '♣', '♦'],
      ranks = [6, 7, 8, 9, 10, 'J', 'Q', 'K', 'A'];
var cards = [];
for (let i = 0; i < suits.length; i++) {
  // I fixed your bug below--it used to be i++, not j++
  for (let j = 0; j < ranks.length; j++) { 
    var colour = 'black';
    if (suits[i] === '&hearts;' || suits[i] === '&diam;') {
      colour = 'red';
    }
    cards.push({
      suit : suits[i],
      rank : ranks[j],
      colour : colour,
      value : j+1
    });              
  }
}
console.log(cards);

嗯，你看，当你

let j = 0; j < ranks.length; i++) 

该循环永远运行，因为j始终为0.很有趣，那就是。