下面这样也可以，不用 this ，用 iterator 就可以 class makeIterator { constructor(arr) { arr[Symbol.iterator] = function () { let i = 0, j = 0; return { next () { if (i >= arr.length) return { value: undefined, done: true }; let value = arr[i][j]; j++; if (j >= arr[i].length) { i++; j = 0; } return { value, done: false }; } } } this.iterator = arr[Symbol.iterator](); } next () { return this.iterator.next().value } } let m = new makeIterator([[1, 4, 7], [2, 9], [8, 7, 6, 3]]); console.log(m.next()); console.log(m.next()); console.log(m.next()); console.log(m.next()); console.log(m.next()); console.log(m.next()); console.log(m.next()); console.log(m.next());