javascript - 如何根据起始索引循环/环绕数组？

Question

var ZODIAC = ["RAT", "OX", "TIGER", "RABBIT", "DRAGON", "SNAKE", "HORSE", "SHEEP", "MONKEY", "ROOSTER", "DOG", "PIG"];
var STARTING_ZODIAC = "MONKEY";

如何打印该数组中以 Monkey 开头并以 Sheep 结尾的所有元素？

Answer 1

您可以使用模运算符，以便索引变量在达到 ZODIAC 数组的长度后回绕到 0:

const ZODIAC = ["RAT", "OX", "TIGER", "RABBIT", "DRAGON", "SNAKE", "HORSE", "SHEEP", "MONKEY", "ROOSTER", "DOG", "PIG"];
const STARTING_ZODIAC = "MONKEY";
const startIndex = ZODIAC.indexOf(STARTING_ZODIAC);

console.log(STARTING_ZODIAC);
for (let i = startIndex + 1; i !== startIndex; i = (i + 1) % ZODIAC.length) {
  console.log(ZODIAC[i]);
}

另一种方法是先将数组的两部分切片成正确的顺序:

const ZODIAC = ["RAT", "OX", "TIGER", "RABBIT", "DRAGON", "SNAKE", "HORSE", "SHEEP", "MONKEY", "ROOSTER", "DOG", "PIG"];
const STARTING_ZODIAC = "MONKEY";
const startIndex = ZODIAC.indexOf(STARTING_ZODIAC);

[
   ...ZODIAC.slice(startIndex),
   ...ZODIAC.slice(0, startIndex)
].forEach(str => console.log(str));