Mastering the art of correctly utilizing splice and slice

Question

Mastering the art of correctly utilizing splice and slice

I'm having trouble identifying the issue in my code. Despite reading numerous articles on slice and splice, I am unable to achieve the desired outcome in my Angular project (not using both methods simultaneously). The results are not as expected. Below is the snippet of my code:

Snippet with slice:

newArray:string[];
mutatedArray:string[];

removeOneFruit() {
  this.newArray=['Apple', 'Orange', 'Plums', 'Grapes'];
  console.log("Before slicing: "+this.newArray);
  this.mutatedArray=this.newArray.slice(this.newArray.indexOf('Orange'),1);
  console.log("After slicing: "+this.mutatedArray);
}

Output:

Before slicing: Apple,Orange,Plums,Grapes

After slicing:

The result after slicing is simply blank. No errors or warnings appear on the console. This behavior puzzles me.

Snippet with splice:

newArray:string[];
mutatedArray:string[];

removeOneFruit() {
  this.newArray=['Apple', 'Orange', 'Plums', 'Grapes'];
  console.log("Before splicing: "+this.newArray);
  this.mutatedArray=this.newArray.splice(this.newArray.indexOf('Orange'),1);
  console.log("After splicing: "+this.mutatedArray);
}

Output:

Before slicing: Apple,Orange,Plums,Grapes

After slicing: Orange

The obtained output is unexpected. I anticipate an array containing all fruits except for Orange. Please advise accordingly.

PS: It's a simplified representation of a larger project where the items are not fruits and are not hardcoded either.

javascript typescript

Answer 1

Answer №1

.splice() function returns the elements that were deleted, but if you execute it on a separate line:

var fruits = ['Apple', 'Orange', 'Plums', 'Grapes'];

fruits.splice(fruits.indexOf('Orange'), 1);

console.log(fruits);

Alternatively, you can achieve similar results using .slice() method in the following way (though it's a bit lengthy):

var fruits = ['Apple', 'Orange', 'Plums', 'Grapes'];

// This code snippet slices the array from the beginning to "Orange", then combines the values after "Orange"
console.log(fruits.slice(0, fruits.indexOf('Orange')).concat(fruits.slice(fruits.indexOf('Orange') + 1, fruits.length)));

Answer 2

.splice() function returns the elements that were deleted, but if you execute it on a separate line:

var fruits = ['Apple', 'Orange', 'Plums', 'Grapes'];

fruits.splice(fruits.indexOf('Orange'), 1);

console.log(fruits);

Alternatively, you can achieve similar results using .slice() method in the following way (though it's a bit lengthy):

var fruits = ['Apple', 'Orange', 'Plums', 'Grapes'];

// This code snippet slices the array from the beginning to "Orange", then combines the values after "Orange"
console.log(fruits.slice(0, fruits.indexOf('Orange')).concat(fruits.slice(fruits.indexOf('Orange') + 1, fruits.length)));

Answer 3

Answer №2

It's important to note that slice and splice function differently

Array.slice requires two parameters: start and end. In the first function provided, using the start index of 'Orange' and an end index of 1 doesn't quite make sense because slice retrieves items within a range, and there are no items between those specified indexes.

In the code snippet provided, you can see that by adjusting the indices to be inclusive, it allows for proper slicing. For example, starting at the index of 'Orange' and then moving one index up will correctly pull the item 'Orange' from the array.

let newArray;
let mutatedArray;

function removeOneFruit() {
  newArray=['Apple', 'Orange', 'Plums', 'Grapes'];
  console.log("Before slicing: "+newArray);
  mutatedArray=newArray.slice(newArray.indexOf('Orange'), newArray.indexOf('Orange')+1);
  console.log("After slicing: "+mutatedArray);
}

removeOneFruit()

As for the second function, it utilizes splice which is specifically used for removing items from an array. Array.splice takes an index and the number of items to remove at that index. By running this function, you can effectively create a new array with the removed item or items. If the goal is to return an array without 'Orange', then utilizing splice to remove 'Orange' and assigning the new value to the mutatedArray accomplishes this task.

let newArray;
let mutatedArray;

function removeOneFruit() {
  newArray=['Apple', 'Orange', 'Plums', 'Grapes'];
  console.log("Before splicing: "+newArray);
  newArray.splice(newArray.indexOf('Orange'),1);
  mutatedArray= newArray;
  console.log("After splicing: "+mutatedArray);
}

removeOneFruit()

Answer 4

It's important to note that slice and splice function differently

Array.slice requires two parameters: start and end. In the first function provided, using the start index of 'Orange' and an end index of 1 doesn't quite make sense because slice retrieves items within a range, and there are no items between those specified indexes.

In the code snippet provided, you can see that by adjusting the indices to be inclusive, it allows for proper slicing. For example, starting at the index of 'Orange' and then moving one index up will correctly pull the item 'Orange' from the array.

let newArray;
let mutatedArray;

function removeOneFruit() {
  newArray=['Apple', 'Orange', 'Plums', 'Grapes'];
  console.log("Before slicing: "+newArray);
  mutatedArray=newArray.slice(newArray.indexOf('Orange'), newArray.indexOf('Orange')+1);
  console.log("After slicing: "+mutatedArray);
}

removeOneFruit()

As for the second function, it utilizes splice which is specifically used for removing items from an array. Array.splice takes an index and the number of items to remove at that index. By running this function, you can effectively create a new array with the removed item or items. If the goal is to return an array without 'Orange', then utilizing splice to remove 'Orange' and assigning the new value to the mutatedArray accomplishes this task.

let newArray;
let mutatedArray;

function removeOneFruit() {
  newArray=['Apple', 'Orange', 'Plums', 'Grapes'];
  console.log("Before splicing: "+newArray);
  newArray.splice(newArray.indexOf('Orange'),1);
  mutatedArray= newArray;
  console.log("After splicing: "+mutatedArray);
}

removeOneFruit()

Answer 5

Answer №3

The reason Slice is not returning any output is because the second parameter actually signifies the end index. In this case, with Orange at index 1 and an end index also set as 1, no value will be returned.

On the other hand, Splice will return the items that were deleted from the original array, impacting the array itself.

Answer 6

The reason Slice is not returning any output is because the second parameter actually signifies the end index. In this case, with Orange at index 1 and an end index also set as 1, no value will be returned.

On the other hand, Splice will return the items that were deleted from the original array, impacting the array itself.

Answer 7

Answer №4

Take a look at the documentation!

newArray.slice(newArray.indexOf('Orange'), 1);

This function slices a portion of an array starting from the index newArray.indexOf('Orange') (which is 1) up to, but not including index 1. This results in an empty array.

If you want to slice a segment of length 2 from a specific position, you can use this example:

var a = [100, 200, 300, 400];
var pos = a.indexOf(200);
a.slice(pos, pos + 2);  // == [ 200, 300 ]

If your goal is to remove a certain element from the array, it's better to do so by filtering it out:

const newArray = ['Apple', 'Orange', 'Plums', 'Grapes'];

// Remove the first 'Orange'.
const orangeIx = newArray.indexOf('Orange');
console.log('Removed by index:', 
            newArray.filter((ignoredValue, index) => index != orangeIx));

// Remove every 'Orange'.
console.log('Removed by value:',
            newArray.filter(fruit => fruit != 'Orange'));

Keep in mind that the above method creates a new shallow copy of the original array instead of muting it directly.

Answer 8

Take a look at the documentation!

newArray.slice(newArray.indexOf('Orange'), 1);

This function slices a portion of an array starting from the index newArray.indexOf('Orange') (which is 1) up to, but not including index 1. This results in an empty array.

If you want to slice a segment of length 2 from a specific position, you can use this example:

var a = [100, 200, 300, 400];
var pos = a.indexOf(200);
a.slice(pos, pos + 2);  // == [ 200, 300 ]

If your goal is to remove a certain element from the array, it's better to do so by filtering it out:

const newArray = ['Apple', 'Orange', 'Plums', 'Grapes'];

// Remove the first 'Orange'.
const orangeIx = newArray.indexOf('Orange');
console.log('Removed by index:', 
            newArray.filter((ignoredValue, index) => index != orangeIx));

// Remove every 'Orange'.
console.log('Removed by value:',
            newArray.filter(fruit => fruit != 'Orange'));

Keep in mind that the above method creates a new shallow copy of the original array instead of muting it directly.

Mastering the art of correctly utilizing splice and slice

Answer №1

Answer №2

Answer №3

Answer №4

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