Question

我有一个像var aa = ["a","b","c","d","e","f","g","h","i","j","k","l"];这样的数组我想删除偶数索引上的元素。所以输出将是行aa = ["a","c","e","g","i","k"];

我试过这种方式

for (var i = 0; aa.length; i = i++) {
if(i%2 == 0){
    aa.splice(i,0);
}
};

但它没有用。

Answer 1

使用 Array#filter 方法

var aa = ["a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l"];

var res = aa.filter(function(v, i) {
  // check the index is odd
  return i % 2 == 0;
});

console.log(res);

如果要更新现有阵列，请执行以下操作：

var aa = ["a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l"],
    // variable for storing delete count
  dCount = 0,
    // store array length
  len = aa.length;

for (var i = 0; i < len; i++) {
  // check index is odd
  if (i % 2 == 1) {
    // remove element based on actual array position 
    // with use of delete count
    aa.splice(i - dCount, 1);
    // increment delete count
    // you combine the 2 lines as `aa.splice(i - dCount++, 1);`
    dCount++;
  }
}


console.log(aa);

以相反顺序迭代循环的另一种方法（从最后一个元素到第一个元素）。

var aa = ["a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l"];

// iterate from last element to first
for (var i = aa.length - 1; i >= 0; i--) {
  // remove element if index is odd
  if (i % 2 == 1)
    aa.splice(i, 1);
}


console.log(aa);

Answer 2

您可以通过执行此操作删除所有备用索引

＆＃13;

var aa = ["a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l"];

for (var i = 0; i < aa.length; i++) {
  aa.splice(i + 1, 1);
}

console.log(aa);

＆＃13;

＆＃13; 或者如果你想存储在不同的数组中，你可以这样做。

＆＃13;

var aa = ["a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l"];

var x = [];
for (var i = 0; i < aa.length; i = i + 2) {
  x.push(aa[i]);
}

console.log(x);

＆＃13;

Answer 3

您可以使用.filter()

 aa =  aa.filter((value, index) => !(index%2));

Answer 4

您可以使用如下的临时变量。

var a = [1,2,3,4,5,6,7,8,9,334,234,234,234,6545,7,567,8]

var temp = [];
for(var i = 0; i<a.length; i++)
   if(i % 2 == 1)
      temp.push(a[i]);

a = temp;

Answer 5

在Ecmascript 6中，

var aa = ["a","b","c","d","e","f","g","h","i","j","k","l"];
var bb = aa.filter((item,index,arr)=>(arr.splice(index,1)));
console.log(bb);

Answer 6

const aa = ["a","b","c","d","e","f","g","h","i","j","k","l"];
let bb = aa.filter((items, idx) => idx % 2 !== 0)

如何从数组中删除所有奇数索引（例如：a [1]，a [3] ..）值

6 个答案: