在每个nt-h数组元素之后插入新元素 [英] Insert new element after each nt-h array elements

问题描述

我有一个名为a的数组，我想在数组a的每个nt-h元素之后插入一个元素.例如，我想将字符串XXX放在数组a的每个3元素之后，结果得到一个新的数组b，如下面的示例所示:

 let a = [undefined, "", 0, [], "ee", false, null, {},  Date(), true, (z)=>2*z, Array(0), NaN ];

let b = [undefined, "", 0, "XXX", [], "ee", false, "XXX", null, {}, Date(), "XXX", true, (z)=>2*z, [], "XXX", NaN];

console.log(a, b); 

我试图通过这种方式做到这一点:

b = [];
a.map((x, i) => b.push((i + 1) % 3 ? x : "XXX"));

https://jsfiddle.net/Lamik/vjfaqn3u/16/

但是，有一个问题:输出b数组的长度与输入a的长度相同，这是错误的.有什么想法或替代解决方案吗?

(更新:就地解决方案也可以；我剪切了数组a)

解决方案

 let a= [undefined, "", 0, [], "ee", false, null, {},  Date(), true, (z)=>2*z, Array(0), NaN ];
  
let n = 3+1;
let currentPosition = 3;
let temp ='xxxxxx';

console.log('Before assignment:::',a.length, a);

while(currentPosition <= (a.length+1)){
   a.splice(currentPosition,0,temp);
   currentPosition += n;
}

console.log('new array length:::::',a.length ,a); 

我希望这个解决方案对您来说很好. 在插入元素之前，长度为13.在17.之后.

I have an array called a and I want to insert an element after every nt-h elements of the array a. For example, I want to put the string XXX after each 3 elements of the array a and as result get a new array b as shown on the next example:

let a = [undefined, "", 0, [], "ee", false, null, {},  Date(), true, (z)=>2*z, Array(0), NaN ];

let b = [undefined, "", 0, "XXX", [], "ee", false, "XXX", null, {}, Date(), "XXX", true, (z)=>2*z, [], "XXX", NaN];

console.log(a, b);

I have tried to do it in this way:

b = [];
a.map((x, i) => b.push((i + 1) % 3 ? x : "XXX"));

https://jsfiddle.net/Lamik/vjfaqn3u/16/

However, there is a problem: The output b array has the same length as input a which is wrong. Any idea or alternative solution?

(UPDATE: in-place solutions are also ok; I cut array a)

解决方案

let a= [undefined, "", 0, [], "ee", false, null, {},  Date(), true, (z)=>2*z, Array(0), NaN ];
  
let n = 3+1;
let currentPosition = 3;
let temp ='xxxxxx';

console.log('Before assignment:::',a.length, a);

while(currentPosition <= (a.length+1)){
   a.splice(currentPosition,0,temp);
   currentPosition += n;
}

console.log('new array length:::::',a.length ,a);

I hope this solution will be fine for you. Before inserting the element a length is 13. After 17.

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