如何获取数组的所有索引

var arr = [1, 2, 3, 4, 5];
var indexes = [];
for (var i = 0; i < arr.length; i++) {
  indexes.push(i);
}
console.log(indexes); // 输出 [0, 1, 2, 3, 4]

var arr = [1, 2, 3, 4, 5];
var indexes = arr.map(function(value, index) {
  return index;
});
console.log(indexes); // 输出 [0, 1, 2, 3, 4]

var arr = [1, 2, 3, 4, 5];
var indexes = Array.from(arr.keys());
console.log(indexes); // 输出 [0, 1, 2, 3, 4]