const factory = length => Array.apply(null, { length }) const craeteArr = factory(10).map((item, index) => index) const arr1 = factory(10).map((item, index) => craeteArr) test: for(let i = 0; i < arr1.length; i++) { for(let j = 0; j < arr1[i].length; j++) { if (i * 10 + j === 88) break test console.log(i * 10 + j) } }