CODEWITHSUNDEEP
javascript
Alexey
Alexey

Reputation: 61

Javascript for loop and splice function

Good day, I have been trying to solve JS problem where I have an array a = [1, 1, 1, 2, 1, 3, 4]. I have to loop through an array and remove every three elements ie (1,1,1) do some logic, then the next three (1,1,2), and so on.

I have used for loop and splice

a = [1, 1, 1, 2, 1, 3, 4]
tuple = ()

    for(j=0; j < a.length; j++){
        tuple = a.splice(j, 3)
    }

However, loop would not go beyond first round of (1,1,1). What would be the correct way to loop through this array and remove sets of every three elements. thank you.

Upvotes: 0

Views: 103

Answers (2)

Ajeet Shah
Ajeet Shah

Reputation: 19813

splice changes the original array and that must be causing your issue.

So, you can use slice which returns a shallow copy of a portion of the original array (without modifying the original array):

const a = [1, 1, 1, 2, 1, 3, 4]

const doLogic = (arr) => {
  console.log(JSON.stringify(arr)) // JSON.stringify is only for one-liner print. You can ignore it.
}

for (let i = 0; i < a.length - 2; i++) {
  const picked = a.slice(i, i + 3)
  doLogic(picked)
}

Or this, if you want to pick the full array when length is less than 3:

if (a.length < 3) {
  doLogic(a)
} else {
  for (let i = 0; i < a.length - 2; i++) {
    const picked = a.slice(i, i + 3)
    doLogic(picked)
  }
}

Upvotes: 0

Kishieel
Kishieel

Reputation: 2053

Splice return removed elements from base array in given range. You probable want to use slice which only copy them and doesn't change primary array. You can also check this solution.

let a = [1, 1, 1, 2, 1, 3, 4];

for (j = 0; j < a.length; j++) {
    if ( j < a.length - 2 ) {
        const touple = [ a[j], a[j+1], a[j+2] ]
        console.log( touple )
    }
}

Upvotes: 1

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