I want to remove the negative elements of the copied array by pop() method but it removes only the last element of the array. Anyone knows where's the problem? The code is in the image
I tried:
const scores = [128, 0, -8, 50, 2, 3];
const betterScores = Array.from(scores);
for (const s of betterScores) {
if (s < 0) {
betterScores.pop(s);
}
}
console.log(betterScores);I wanted to have betterScores = [128,50,2,3] but I got [128,0,-8,50,2].
Use filter instead of for loop:
const betterScores = scores.filter(s => s > 0);
Array.filter() to improve it. You can also add a link to the documentation of Array.pop() to help the OP understand why their approach does not work.
pop method does not expect any arguments, it automatically removes last element of array. To remove element at an index you can use splice method.
const arrayOfNumbers = [1, 2, 3, 4];
arrayOfNumbers.splice(1, 1);
console.log(arrayOfNumbers); // [1, 3, 4]
So to remove one element at an index you would use splice(n, 1), where n is index if element you are removing and 1 is count of elements(for your case you would default 2nd argument to 1 and just give right index. Also to have access to index for of loop wont work. Use basic for loop or forEach to have access to index
You can do easily by filter in javascript.
Try this:
Filter method doc: Filter Method
const scores = [128, 0, -8, 50, 2, 3];
const betterScores = Array.from(scores);
const result = betterScores.filter(item => item > 0);
console.log(result);Array.filter() to improve it. You can also add a link to the documentation of Array.pop() to help the OP understand why their approach does not work.
filter is the best approach to use to solve this problem as the other users have commented.
To answer the specific question about why your code doesn't work:
The
pop()method removes the last element from an array and returns that element. This method changes the length of the array. (my emphasis)
If you really wanted to use a loop to remove elements you might use a simple for loop and splice elements from a particular index. But since the length of the array gets shorter when you remove elements it's usually best to start from the end of the array, and iterate toward the start.
const scores = [128, 0, -8, 50, 2, 3];
for (let i = scores.length - 1; i >= 0; --i) {
if (scores[i] <= 0) {
scores.splice(i, 1);
}
}
console.log(scores);I'm sure you are not aware of pop method of array, It pop last element of you array. If you task is to only get positive number then using filter would be better solution
const scores = [128, 0, -8, 50, 2, 3];
const result = scores.filter(item => item >= 0);
console.log(result);but if you task is to do using some method to manually remove element form array you can use splice method something like this
const scores = [128,0,-8,50,2,3];
const betterScores = Array.from(scores);
for(const s in betterScores){
if(betterScores[s] < 0){
betterScores.splice(s,1);
}
}
console.log(betterScores);you may try this code:
const scores = [128, 0, -8, 50, 2, 3];
const betterScores = Array.from(scores);
for (const s of betterScores) {
if (s < 0) {
betterScores.splice(betterScores.indexOf(s), 1)
}
}
Array.pop()? It does not accept arguments (it ignores them, in fact) and always removes the last element of the array. UseArray.filter()to produce the array you need.