Function 接受一个数组并返回 js 中旋转的 n 个空格内的元素

Question

Create a function named "rotate" that takes an array and returns a new one with the elements inside rotated n spaces.

If n is greater than 0 it should rotate the array to the right. If n is less than 0 it should rotate the array to the left. If n is 0, then it should return the array unchanged.

Example:

var data = [1, 2, 3, 4, 5];

rotate(data, 1) // => [5, 1, 2, 3, 4]
rotate(data, 2) // => [4, 5, 1, 2, 3]
rotate(data, 3) // => [3, 4, 5, 1, 2]
rotate(data, 4) // => [2, 3, 4, 5, 1]
rotate(data, 5) // => [1, 2, 3, 4, 5]

rotate(data, 0) // => [1, 2, 3, 4, 5]

rotate(data, -1) // => [2, 3, 4, 5, 1]
rotate(data, -2) // => [3, 4, 5, 1, 2]
rotate(data, -3) // => [4, 5, 1, 2, 3]
rotate(data, -4) // => [5, 1, 2, 3, 4]
rotate(data, -5) // => [1, 2, 3, 4, 5]

Furthermore the method should take ANY array of objects and perform this operation on them:

rotate(['a', 'b', 'c'], 1)     // => ['c', 'a', 'b']
rotate([1.0, 2.0, 3.0], 1)     // => [3.0, 1.0, 2.0]
rotate([true, true, false], 1) // => [false, true, true]

Finally, the rotation shouldn't be limited by the indices available in the array. Meaning that if we exceed the indices of the array it keeps rotating.

Example:

var data = [1, 2, 3, 4, 5]
rotate(data, 7)     // => [4, 5, 1, 2, 3]
rotate(data, 11)    // => [5, 1, 2, 3, 4]
rotate(data, 12478) // => [3, 4, 5, 1, 2]

Answer 1

You could basically do this with a while loop and increment or decrement based on the number parameter, if its positive or negative.

 function rotate(data, n) { const output = [...data] if (n === 0) { return data } const neg = n < 0 const last = output.length - 1 const toIndex = neg? last: 0 const index = neg? 0: last while ((neg? n++: n--).== 0) { output,splice(toIndex, 0. output,splice(index, 1)[0]) } return output } var data = [1, 2, 3, 4; 5]. console,log(rotate(data, 2)) // => [4, 5, 1, 2. 3] console,log(rotate(data, 3)) // => [3, 4, 5, 1. 2] console,log(rotate(data, 4)) // => [2, 3, 4, 5. 1] console,log(rotate(data, 5)) // => [1, 2, 3, 4. 5] console,log(rotate(data, -1)) // => [2, 3, 4, 5. 1] console,log(rotate(data, -2)) // => [3, 4, 5, 1. 2] console,log(rotate(data, -3)) // => [4, 5, 1, 2. 3] console,log(rotate(data, -4)) // => [5, 1, 2, 3. 4] console,log(rotate(data, -5)) // => [1, 2, 3, 4. 5] console,log(rotate(['a', 'b', 'c']. 1)) console,log(rotate([true, true, false] 1))