CODEWITHSUNDEEP
javascript
methuselah
methuselah

Reputation: 13206

Remove last element from array if it matches a particular condition

What's the best way to remove the last element from an array if it matches a particular value?

For instance:

components = dedupeLast(components, '<app-builder-placeholder></app-builder-placeholder>');

function dedupeLast(a, target) {
  for(let i = 0; i < a.length; i++){
    if (i === a.length) {
      if(a[i] === target)
      a.splice(i, 1);
    }
  }
}

Upvotes: 1

Views: 1682

Answers (3)

Olafant
Olafant

Reputation: 828

Since array.splice creates a new Array and copies the removed elements to it, I would use array.pop instead for better performance.

function dedupeLast(a, target) {
  let temp;
  if(a.length && a[a.length - 1] === target){
    temp = a.pop();
  }
}

Array.prototype.pop() just removes the last element an returns it. If you check before, if that element equals target, there is no need to pop and push. If you need the removed element for something else, you can just use temp.

Upvotes: 1

ibrahim mahrir
ibrahim mahrir

Reputation: 31682

If it's the last element you're after then you don't need the loop at all, just check if the array is empty or not and access the last element directly:

function dedupeLast(a, target) {
   if(a.length && a[a.length - 1] === target){
      a.pop();
   }
}

It reads: if a is not empty (a.length != 0) and the last element a[a.length - 1] === target then, remove the last element using pop.

Upvotes: 3

Akshay Bande
Akshay Bande

Reputation: 2587

You can use pop, to access last element if it satisfies the criteria remove it else add it again.

function dedupeLast(a, target) {
  
  let temp = a.pop();
  if(temp === target){
    return;
  }
  else{
    a.push(temp);
  }
  
}

Upvotes: 1

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