为什么下面代码中map()的输出结果会有差异?
var y = [1,2,2,1];
var t = y.map(ind => [...Array(ind)].map((_,i) => ind+""+i));
// This makes [ [ '10' ], [ '20', '21' ], [ '20', '21' ], [ '10' ] ]
var t1 = y.map(ind => Array(ind).map((_,i) => ind+""+i));
//[ [ <1 empty item> ], [ <2 empty items> ], [ <2 empty items> ], [ <1 empty item> ] ]
.map
不会循环遍历离散的索引。 - RajeshArray.from({length: n}, (_, i) => ...)
。 - Rajesh