Why Last Value of Array is Easy to Remove
JavaScript | Remove the last item from an array
The task is to remove the last item from the array. Here are a few of the most preferred methods discussed. First few functions to understand.
- JavaScript Array splice() method This method adds/deletes items to/from the array, and returns the deleted item(s).
Syntax:
array.splice(index, number, item1, ....., itemN)
Parameters:
- index: This parameter is required. It specifies the integer at what position to add/remove items, Negative values are used to specify the position from the end of the array.
- number: This parameter is optional. It specifies the number of items to be removed. 0 means, nothing to remove.
- item1, ….., itemN: This parameter is optional. This specifies the new item(s) to be added to the array.
Return value:
Returns a new Array, having the removed items.
- JavaScript Array slice() Method
This method returns a new array containing the selected elements. This method selects the elements starts from the given start argument and ends at, but excluding the given end argument.
Syntax:
array.slice(start, end)
Parameters:
- start: This parameter is optional. It specifies the integer from where to start the selection (first element is at index 0). Negative numbers are used to select from the end of the array. If not used, it acts like "0"
- end: This parameter is optional. It specifies the integer from where to end the selection. If not used, all elements from the start to the end of array will be included in selection. Negative numbers are used to select from the end.
Return value:
Returns a new Array, having the selected items.
- JavaScript Array pop() Method This method deletes the last element of an array and returns the element.
Syntax:
array.pop()
Return value: It returns the removed array item. An array item can be a string, a number, an array, a boolean, or any other object types that are applicable in an array.
- The arr.reduce() Method: The reduce method in JavaScript is used to reduce the array to a single value and executes a provided function for each value of the array and the return value of the function is stored in an accumulator.
Syntax:
array.reduce( function(total, currentValue, currentIndex, arr), initialValue )
Example 1: This example removes the last item from the array using splice() method.
HTML
<!DOCTYPE HTML>
< html >
< head >
< title >
JavaScript
| Remove last item from array.
</ title >
</ head >
< body style = "text-align:center;"
id = "body" >
< h1 style = "color:green;" >
GeeksForGeeks
</ h1 >
< p id = "GFG_UP"
style = "font-size: 16px;" >
</ p >
< button onclick = "gfg_Run()" >
remove
</ button >
< p id = "GFG_DOWN"
style="color:green;
font-size: 20px;
font-weight: bold;">
</ p >
< script >
var el_up =
document.getElementById("GFG_UP");
var el_down =
document.getElementById("GFG_DOWN");
var array = [34, 24, 31, 48];
el_up.innerHTML = "Array = [" + array + "]";
function gfg_Run() {
array.splice(-1, 1);
el_down.innerHTML =
"Remaining array = [" + array + "]";
}
</ script >
</ body >
</ html >
Output:
- Before clicking on the button:
- After clicking on the button:
Example 2: This example removes the last item from the array using pop() method.
HTML
<!DOCTYPE HTML>
< html >
< head >
< title >
JavaScript
| Remove last item from array.
</ title >
</ head >
< body style = "text-align:center;"
id = "body" >
< h1 style = "color:green;" >
GeeksForGeeks
</ h1 >
< p id = "GFG_UP"
style = "font-size: 16px;" >
</ p >
< button onclick = "gfg_Run()" >
remove
</ button >
< p id = "GFG_DOWN"
style="color:green;
font-size: 20px;
font-weight: bold;">
</ p >
< script >
var el_up =
document.getElementById("GFG_UP");
var el_down =
document.getElementById("GFG_DOWN");
var array = [34, 24, 31, 48];
el_up.innerHTML = "Array = [" + array + "]";
function gfg_Run() {
array.pop();
el_down.innerHTML =
"Remaining array = [" + array + "]";
}
</ script >
</ body >
</ html >
Output:
- Before clicking on the button:
- After clicking on the button:
Example 3: This example does not remove the last item from the array but returns a new array in which the item is removed, using splice() method.
HTML
<!DOCTYPE HTML>
< html >
< head >
< title >
JavaScript
| Remove last item from array.
</ title >
</ head >
< body style = "text-align:center;"
id = "body" >
< h1 style = "color:green;" >
GeeksForGeeks
</ h1 >
< p id = "GFG_UP"
style = "font-size: 16px;" >
</ p >
< button onclick = "gfg_Run()" >
remove
</ button >
< p id = "GFG_DOWN"
style="color:green;
font-size: 20px;
font-weight: bold;">
</ p >
< script >
var el_up = document.getElementById("GFG_UP");
var el_down = document.getElementById("GFG_DOWN");
var array = [34, 24, 31, 48];
el_up.innerHTML = "Array = [" + array + "]";
function gfg_Run() {
el_down.innerHTML =
"Remaining array = [" + array.slice(0, -1) + "]";
}
</ script >
</ body >
</ html >
Output:
- Before clicking on the button:
- After clicking on the button:
Example 4: This example removes the last item from the array using arr.reduce() method.
HTML
<!DOCTYPE HTML>
< html >
< head >
< title >
JavaScript
| Remove last item from array.
</ title >
</ head >
< body style = "text-align:center;"
id = "body" >
< h1 style = "color:green;" >
GeeksForGeeks
</ h1 >
< p id = "GFG_UP"
style = "font-size: 16px;" >
</ p >
< button onclick = "gfg_Run()" >
remove
</ button >
< p id = "GFG_DOWN"
style="color:green;
font-size: 20px;
font-weight: bold;">
</ p >
< script >
var el_up =
document.getElementById("GFG_UP");
var el_down =
document.getElementById("GFG_DOWN");
var array = [34, 24, 31, 48];
el_up.innerHTML = "Array = [" + array + "]";
function gfg_Run() {
array = array.filter((item, i)=> i!=(array.length-1));
el_down.innerHTML =
"Remaining array = [" + array + "]";
}
</ script >
</ body >
</ html >
Output:
Array.filter method
Source: https://www.geeksforgeeks.org/javascript-remove-the-last-item-from-an-array/
0 Response to "Why Last Value of Array is Easy to Remove"
Post a Comment