從 JavaScript 數組中刪除特定索引

Question

我寫了一些代碼來跟蹤我成功的索引，但發現很難將它們從數組中刪除，所以我對剩下的做了同樣的事情。

 var v = [4, 7, 2,5, 3] 
 var f = []
 for (let i = 1; i < v.length; i += 2){
/*(point1)this line doesn't seem to work*/
 if (v[i] > v[i] - 1)
/*(point 2) Instead of console.log I want to delete every of v[i] */
console.log(v[i])

輸出

7
5

刪除 v[I] 時的預期輸出

 v = [4,2,3]

最好我想做一些類似 splice v[i] 如果 v[i] > v[i] -1 的事情，然后像拼接元素一樣返回 v。

我首先在命令行中使用這種類似的邏輯測試了第 1 點，但它工作正常，但是.....;

   if ((b[1] -1) > b[0]){console.log(b[2])}

輸出

3
```

Answer 1

要刪除數組的特定索引，您可以使用如下拼接。

var fruits = ["apple", "orange", "avocado", "banana"];
//remove one element starting from index 2
var removed = fruits.splice(2, 1);
//fruits is ["apple", "orange", "banana"]
//removed is ["avocado"]

但是，關於 if 邏輯，它將始終為真，因為您正在測試一個數字是否大於其自身減去 1。如果您嘗試測試當前數組位置中的值是否大於前一個位置中的值，所以你應該這樣。

if (v[i] > v[i-1])

Answer 2

通過從數組v消除不需要的元素來構建新的數組res

 var v = [4, 7, 2, 5, 3]; var res = []; res.push(v[0]); for (let i = 1; i < v.length; i += 1) { if (v[i - 1] > v[i]) { res.push(v[i]); } } console.log(res);

Answer 3

嘗試數組對象的filter 方法。

您可以使用數組對象的 filter 方法過濾掉所需的值並獲取新數組，而不是從當前數組中刪除元素。

 var arr = [0, 1, 2, 3]; var filteredArr = arr.filter(function(element, currentIndex, arrObj) { //currentIndex and arrObj can be used to form your desired condition but they are //optional parameter // below is the filter condition to be applied on each element return element > 0; }); console.log('filteredArr will have all the elements of the array which satisfies the filter condition:', filteredArr);