Splice Javascript

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The JavaScript splices () method modifies an array. It allows you to add new elements to a table or delete or modify those that already exist. splice () changes the array on which it is used. It does not create a new table.

It is common to want to add or remove items from a list of existing items. For example, let’s say you have a program that provides feedback from employees. An employee is on vacation. You can temporarily remove them from your program.

You can use splice () to add elements, remove elements, or modify elements in an array. This method allows you to add or remove elements from an array. In this tutorial, we’ll show how the splice () method works and how to use it in JavaScript code.

Update Array

The contents of an array can include numbers, strings, and Booleans. In JavaScript, you can use a array to store more information instead of storing data in multiple variables. For example, if you have a class of ten students, you can create an array to list each of their names.

Arrays can be viewed using their index numbers, which start at 0. Here is an example array:

JavaScript splice ()

The JavaScript splice () method adds, modifies, or removes an element from an array. splice () modifies an existing array

Either look at the syntax for splice ():.

splice () accepts three parameters:

  • The index starting number of (required)
  • the number of array elements you want to remove ( optional)
  • the elements to add to the list ( optional)

you can add multiple items to a list using junction. to do this, you need to specify all the items you want to add as final parameters.

splice () JavaScript: remove from this array

We have a list of student names Paul moved to another school and we want to remove him from our list of names Here is an example of splicing () deleting ... a name from our array:

After running our code, we will get the following output:

["Alex", "Fred", "Molly"]

We deleted the element starting with index "3" In this case, the The JavaScript string that we deleted was "Paul

If we were to remove the second argument from our code, all elements after the index.‚" 3 & rdquo; it would also have been removed

JavaScript splice (). Add to array

If we wanted to add another student to our array, we can also use splice (). If we add a third parameter, we can specify what should be added to the array. Here is an example:

The output of this code is as follows:

["Alex", "Fred", "Molly", "Paul", "Hannah"]

the new string "Hannah" has been added at the end of the array, at index position "4." Note that our second pa rameter was set to 0 because we are not removing anything from our array. Splice makes it easy to add new elements to an array

We could add other names by including additional parameters in our code:.

student var = ["Alex", "Fred", "Molly", "Paul"]

students.splice (4, 0, "Hannah", "Lily") ;

console.log (students);

This code adds both "Hannah" and "Lily" to our list

splice () JavaScript. Add and remove from array

If we want to add and remove elements from an array at the same time, we can also use splice () Here is an example in action.

The output for this code is as follows:

["Alex", "Fred", "Hannah", "Paul"]

Our code removed the element from the array with the index value "2" which was "Molly". So our code added "Hannah" at the index position of "2."

JavaScript Splice vs. Slice

Some developers get confused between JavaScript slice () and splice () because slice () can also be used to remove elements from an array. However, there are differences between these two methods.

First, slice () does not change the original array, whereas (as seen above) the junction changes original vector . Additionally, splice () returns the new array with any changes made, while splice () returns the item removed.

Conclusion

splicing () adds elements to, removes elements from, or modifies elements in an existing array. You can add or remove as many elements from an array as you like using splice ().

This is all you need to know about splice () in JavaScript. In short, if you are looking to add or remove an element from JavaScript arrays, splice () can be a useful function to know.

To learn more about JavaScript, read our guide on best JavaScript tutorials for beginners .

Splice Javascript __del__: Questions

__del__

How can I make a time delay in Python?

5 answers

I would like to know how to put a time delay in a Python script.

2973

Answer #1

import time
time.sleep(5)   # Delays for 5 seconds. You can also use a float value.

Here is another example where something is run approximately once a minute:

import time
while True:
    print("This prints once a minute.")
    time.sleep(60) # Delay for 1 minute (60 seconds).

2973

Answer #2

You can use the sleep() function in the time module. It can take a float argument for sub-second resolution.

from time import sleep
sleep(0.1) # Time in seconds

__del__

How to delete a file or folder in Python?

5 answers

How do I delete a file or folder in Python?

2639

Answer #1


Path objects from the Python 3.4+ pathlib module also expose these instance methods:

Splice Javascript __delete__: Questions

2639

Answer #2


Path objects from the Python 3.4+ pathlib module also expose these instance methods:

2639

Answer #3

Python syntax to delete a file

import os
os.remove("/tmp/<file_name>.txt")

Or

import os
os.unlink("/tmp/<file_name>.txt")

Or

pathlib Library for Python version >= 3.4

file_to_rem = pathlib.Path("/tmp/<file_name>.txt")
file_to_rem.unlink()

Path.unlink(missing_ok=False)

Unlink method used to remove the file or the symbolik link.

If missing_ok is false (the default), FileNotFoundError is raised if the path does not exist.
If missing_ok is true, FileNotFoundError exceptions will be ignored (same behavior as the POSIX rm -f command).
Changed in version 3.8: The missing_ok parameter was added.

Best practice

  1. First, check whether the file or folder exists or not then only delete that file. This can be achieved in two ways :
    a. os.path.isfile("/path/to/file")
    b. Use exception handling.

EXAMPLE for os.path.isfile

#!/usr/bin/python
import os
myfile="/tmp/foo.txt"

## If file exists, delete it ##
if os.path.isfile(myfile):
    os.remove(myfile)
else:    ## Show an error ##
    print("Error: %s file not found" % myfile)

Exception Handling

#!/usr/bin/python
import os

## Get input ##
myfile= raw_input("Enter file name to delete: ")

## Try to delete the file ##
try:
    os.remove(myfile)
except OSError as e:  ## if failed, report it back to the user ##
    print ("Error: %s - %s." % (e.filename, e.strerror))

RESPECTIVE OUTPUT

Enter file name to delete : demo.txt
Error: demo.txt - No such file or directory.

Enter file name to delete : rrr.txt
Error: rrr.txt - Operation not permitted.

Enter file name to delete : foo.txt

Python syntax to delete a folder

shutil.rmtree()

Example for shutil.rmtree()

#!/usr/bin/python
import os
import sys
import shutil

# Get directory name
mydir= raw_input("Enter directory name: ")

## Try to remove tree; if failed show an error using try...except on screen
try:
    shutil.rmtree(mydir)
except OSError as e:
    print ("Error: %s - %s." % (e.filename, e.strerror))

__delete__

Is there a simple way to delete a list element by value?

5 answers

I want to remove a value from a list if it exists in the list (which it may not).

a = [1, 2, 3, 4]
b = a.index(6)

del a[b]
print(a)

The above case (in which it does not exist) shows the following error:

Traceback (most recent call last):
  File "D:zjm_codea.py", line 6, in <module>
    b = a.index(6)
ValueError: list.index(x): x not in list

So I have to do this:

a = [1, 2, 3, 4]

try:
    b = a.index(6)
    del a[b]
except:
    pass

print(a)

But is there not a simpler way to do this?

1055

Answer #1

To remove an element"s first occurrence in a list, simply use list.remove:

>>> a = ["a", "b", "c", "d"]
>>> a.remove("b")
>>> print(a)
["a", "c", "d"]

Mind that it does not remove all occurrences of your element. Use a list comprehension for that.

>>> a = [10, 20, 30, 40, 20, 30, 40, 20, 70, 20]
>>> a = [x for x in a if x != 20]
>>> print(a)
[10, 30, 40, 30, 40, 70]

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