How can I remove a specific item from an array in JavaScript?

arrays, javascript

Solution

Find the `index` of the array element you want to remove using `indexOf`, and then remove that index with `splice`.

The splice() method changes the contents of an array by removing existing elements and/or adding new elements.

const array = [2, 5, 9];

console.log(array);

const index = array.indexOf(5);
if (index > -1) { // only splice array when item is found
  array.splice(index, 1); // 2nd parameter means remove one item only
}

// array = [2, 9]
console.log(array);

The second parameter of `splice` is the number of elements to remove. Note that `splice` modifies the array in place and returns a new array containing the elements that have been removed.

For the reason of completeness, here are functions. The first function removes only a single occurrence (i.e. removing the first match of `5` from `[2,5,9,1,5,8,5]`), while the second function removes all occurrences:

function removeItemOnce(arr, value) {
  var index = arr.indexOf(value);
  if (index > -1) {
    arr.splice(index, 1);
  }
  return arr;
}

function removeItemAll(arr, value) {
  var i = 0;
  while (i < arr.length) {
    if (arr[i] === value) {
      arr.splice(i, 1);
    } else {
      ++i;
    }
  }
  return arr;
}
// Usage
console.log(removeItemOnce([2,5,9,1,5,8,5], 5))
console.log(removeItemAll([2,5,9,1,5,8,5], 5))

In TypeScript, these functions can stay type-safe with a type parameter:

function removeItem<T>(arr: Array<T>, value: T): Array<T> { 
  const index = arr.indexOf(value);
  if (index > -1) {
    arr.splice(index, 1);
  }
  return arr;
}

Problem

How do I remove a specific value from an array? Something like: ``` array.remove(value); ``` Constraints: I have to use core JavaScript. Frameworks are not allowed.

Original source

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