如何阵列的Javascript嵌套添加到项目

Question

所以，如果我想删除数组项筑巢我绝对可以做到这一点：

var nestedArrs = [[1],[2],[3],[4],[5]]; 
var denestedArr = [].concat.apply([], nestedArrs); 
console.log(denestedArr) //prints [1, 2, 3, 4, 5]; 

，但是，如果我需要往回走，并添加嵌套什么？

var unnestedArr = [7, 8, 9, 10]; 
var nestedArr = [] ? // Say I want to add nesting to every other item in arr 
console.log(nestedArr); //so I wanted it to print [[7], 8, [9], 10] 
//& nested Arr needs to be based upon the starting unnestedArr. 

Answer 1

var unnestedArr = [7, 8, 9, 10]; 
 

 
var nestedArr = unnestedArr.map(function(item, index) { 
 
    return index % 2 === 0 ? [ item ] : item; 
 
}); 
 

 
console.log(nestedArr);