When working with arrays in JavaScript, two frequently utilized methods are slice() and splice(). Beginners may find them alike since both operate on arrays and their names are quite comparable. However, they serve distinct functions.
In this article, you will discover both methods, slice() and splice(), along with the primary differences between them and the best practices for using them.
Arrays rank among the most widely used data structures in JavaScript. They are a particular kind of object utilized to store various values of different data types.
To manipulate arrays, you need to read, insert, remove, or substitute elements. JavaScript offers two essential methods for performing such actions. Let’s delve into each of them in detail:
slice() Method
The slice() method is employed to extract a specific segment of an array and return it as a new array, which means it does not alter the original array. Furthermore, the slice() method generates a new array.
Syntax:
array.slice(startIndex, endIndex);
Example 1: Extract Specific Segment From Array
Javascript
Code Copied!
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editor42632.setValue(decodedContent); // Set the default text
editor42632.clearSelection();
editor42632.setOptions({
maxLines: Infinity
});
function decodeHTML42632(input) {
var doc = new DOMParser().parseFromString(input, “text/html”);
return doc.documentElement.textContent;
}
// Function to copy code to clipboard
function copyCodeToClipboard42632() {
const code = editor42632.getValue(); // Get code from the editor
navigator.clipboard.writeText(code).then(() => {
jQuery(“.maineditor42632 .copymessage”).show();
setTimeout(function() {
jQuery(“.maineditor42632 .copymessage”).hide();
}, 2000);
}).catch(err => {
console.error(“Error copying code: “, err);
});
}
function runCode42632() {
var code = editor42632.getSession().getValue();
jQuery.ajax({
url: “https://intellipaat.com/blog/wp-admin/admin-ajax.php”,
type: “post”,
data: {
language: “js”,
code: code,
cmd_line_args: “”,
variablenames: “”,
action:”compilerajax”
},
success: function(response) {
var myArray = response.split(“~”);
var data = myArray[1];
jQuery(“.output42632”).html(“
"+data+"");
jQuery(".maineditor42632 .code-editor-output").show();
jQuery("#runBtn42632 i.run-code").hide();
}
})
}
function closeoutput42632() {
var code = editor42632.getSession().getValue();
jQuery(".maineditor42632 .code-editor-output").hide();
}
// Attach event listeners to the buttons
document.getElementById("copyBtn42632").addEventListener("click", copyCodeToClipboard42632);
document.getElementById("runBtn42632").addEventListener("click", runCode42632);
document.getElementById("closeoutputBtn42632").addEventListener("click", closeoutput42632);
Output:
Explanation: In this demonstration,
``````html
You are utilizing the slice function to obtain a particular segment from an array. Here, startIndex (optional parameter) specifies the index at which to commence extraction, while endIndex (optional parameter) indicates the index at which to cease extraction. The element located at endIndex is excluded from the resulting array.
function closeoutput8760() {
jQuery(".maineditor8760 .code-editor-output").hide();
}
// Attach event listeners to the buttons
document.getElementById("copyBtn8760").addEventListener("click", copyCodeToClipboard8760);
document.getElementById("runBtn8760").addEventListener("click", runCode8760);
document.getElementById("closeoutputBtn8760").addEventListener("click", closeoutput8760);
Output:
Clarification: In this scenario, only the value of startIndex is provided, which will yield a new array containing elements from the 1st index to the last element.
Example 3: Utilizing Negative Indexes
Javascript
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editor69941.setValue(decodedContent); // Set the default content
editor69941.clearSelection();
editor69941.setOptions({
maxLines: Infinity
});
function decodeHTML69941(input) {
var doc = new DOMParser().parseFromString(input, "text/html");
return doc.documentElement.textContent;
}
// Function to copy code to clipboard
function copyCodeToClipboard69941() {
const code = editor69941.getValue(); // Retrieve code from the editor
navigator.clipboard.writeText(code).then(() => {
jQuery(".maineditor69941 .copymessage").show();
setTimeout(function() {
jQuery(".maineditor69941 .copymessage").hide();
}, 2000);
}).catch(err => {
console.error("Error copying code: ", err);
});
}
function runCode69941() {
var code = editor69941.getSession().getValue();
jQuery("#runBtn69941 i.run-code").show();
jQuery(".output-tab").click();
jQuery.ajax({
url: "https://intellipaat.com/blog/wp-admin/admin-ajax.php",
type: "post",
data: {
language: "js",
code: code,
cmd_line_args: "",
variablenames: "",
action: "compilerajax"
},
success: function(response) {
var myArray = response.split("~");
var data = myArray[1];
jQuery(".output69941").html("
function closeoutput69941() {
jQuery(".maineditor69941 .code-editor-output").hide();
}
// Attach event listeners to the buttons
document.getElementById("copyBtn69941").addEventListener("click", copyCodeToClipboard69941);
document.getElementById("runBtn69941").addEventListener("click", runCode69941);
document.getElementById("closeoutputBtn69941").addEventListener("click", closeoutput69941);
``````html
"",
variablenames: "",
action:"compilerajax"
},
success: function(response) {
var myArray = response.split("~");
var data = myArray[1];
jQuery(".output69941").html("
"+data+"");
jQuery(".maineditor69941 .code-editor-output").show();
jQuery("#runBtn69941 i.run-code").hide();
}
})
}
function closeoutput69941() {
var code = editor69941.getSession().getValue();
jQuery(".maineditor69941 .code-editor-output").hide();
}
// Bind event listeners to the buttons
document.getElementById("copyBtn69941").addEventListener("click", copyCodeToClipboard69941);
document.getElementById("runBtn69941").addEventListener("click", runCode69941);
document.getElementById("closeoutputBtn69941").addEventListener("click", closeoutput69941);
Result:
Clarification: Negative indexes in JavaScript initiate from the final element. Therefore, here -2 indicates the second-to-last element in the array. It will yield all remaining elements beginning from the index -2.
When should you utilize slice()?
The slice() is a non-destructive technique as it does not alter the existing array. Here are several typical scenarios for employing the slice() method:
To generate a duplicate of a complete array.
To create a sub-array from a larger array.
To retrieve elements without changing the original array.
The splice() function is employed to modify the content of an array by eliminating, substituting, and adding elements. It does not generate any new array. Additionally, it can alter the original array.
startIndex: The index from which JavaScript initiates changes to the array.
deleteCount: This is an optional parameter that denotes how many elements to remove.
Items: Elements to insert at startIndex. It is also an optional parameter.
Example 1: Remove an Element from a Specified Index
Javascript
Code Copied!
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editor41886.setValue(decodedContent); // Set the default text
editor41886.clearSelection();
editor41886.setOptions({
maxLines: Infinity
});
function decodeHTML41886(input) {
var doc = new DOMParser().parseFromString(input, "text/html");
return doc.documentElement.textContent;
}
// Function to copy code to clipboard
function copyCodeToClipboard41886() {
const code = editor41886.getValue(); // Get code from the editor
navigator.clipboard.writeText(code).then(() => {
// alert("Code copied to clipboard!");
function closeoutput41886() {
var code = editor41886.getSession().getValue();
jQuery(".maineditor41886 .code-editor-output").hide();
}
// Bind event listeners to the buttons
document.getElementById("copyBtn41886").addEventListener("click",
``````html
copyCodeToClipboard41886);
document.getElementById("runBtn41886").addEventListener("click", executeCode41886);
document.getElementById("closeOutputBtn41886").addEventListener("click", hideOutput41886);
Result:
Clarification: In this case, you are utilizing the splice method to eliminate an item from a designated index. Here, the courses.splice(1,1) removes the entry from the initial index, and precisely one element is extracted from the array since the second parameter (deleteCount) is 1.
Illustration 2: Add an item without erasing
Javascript
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editor68950.setValue(decodedContent); // Set the initial text
editor68950.clearSelection();
editor68950.setOptions({
maxLines: Infinity
});
function decodeHTML68950(input) {
var doc = new DOMParser().parseFromString(input, "text/html");
return doc.documentElement.textContent;
}
// Function to duplicate code to clipboard
function copyCodeToClipboard68950() {
const code = editor68950.getValue(); // Retrieve code from the editor
navigator.clipboard.writeText(code).then(() => {
jQuery(".mainEditor68950 .copyMessage").show();
setTimeout(function() {
jQuery(".mainEditor68950 .copyMessage").hide();
}, 2000);
}).catch(err => {
console.error("Error duplicating code: ", err);
});
}
function executeCode68950() {
var code = editor68950.getSession().getValue();
function hideOutput77917() {
var script = editor77917.getSession().getValue();
jQuery(".maineditor77917 .code-editor-output").hide();
}
// Bind event listeners to the buttons
document.getElementById(""copyBtn77917"").addEventListener(""click"", copyCodeToClipboard77917);
document.getElementById(""runBtn77917"").addEventListener(""click"", executeCode77917);
document.getElementById(""closeoutputBtn77917"").addEventListener(""click"", hideOutput77917);
Result:
Clarification: In this instance, remove the element located at the first index (“AI”) and introduce two new entries to the array at the same position (‘CyberSecurity’ and ‘AR/VR’).
When should splice() be utilized??
The splice() is a destructive function as it can alter the original array. Here are some frequent scenarios for using the splice() method:
To add elements at any location in an array.
To delete elements based on index
To reorder elements.
To substitute the element by combining removal and insertion both.
Distinction Between slice() and splice()
Here are the main contrasts between the slice() and splice() functions in JavaScript:
Characteristic
slice()
splice()
Intent
The aim is to extract a segment from an array
It's meant to alter the array.
Original Array
It does not modify the original array. Additionally, it generates a new array.
The original array is altered.
Returned Value
It yields the new array containing selected elements.
It returns an array containing the elements that were removed
Insertion/Deletion
Element insertion and deletion are unsupported.
It accommodates both the addition of new elements and the removal of existing ones.
Use Case
To create subarrays from the primary array.
It is utilized for inserting, deleting, and replacing elements dynamically.
Recommended Practices
The slice() and splice() methods hold significance and are frequently used by developers to manipulate arrays. Here are some considerations to keep in mind while applying slice() and splice() in your code:
If you are passing an array to functions, it is advisable to employ theslice() method. This can safeguard the original array from unintended modifications.
Always keep in mind that the splice() method inherently alters the array. If you wish to maintain the original sequence of an array, then refrain from using splice().
In JavaScript, the slice() method can be utilized to clone an entire array.
To insert an element at a specific position, use the splice() method.
Steer clear of using splice() within loops as it can lead to unexpected outcomes.
Closing Thoughts
Grasping the differences between the slice() and splice() methods is crucial for managing array components in JavaScript. The slice() function enables you to create a subarray and returns it as a new array without modifying the original elements. Conversely, the splice() method offers a dynamic method to adjust the original array by inserting, removing, or substituting its components. If you consistently work with JavaScript, it is vital to become acquainted with the slice() vs splice() methods.
Q1. What distinguishes slice from splice?
The slice() method produces a complete array or a subsection of an array without altering the original array. It yields a new array. The splice() method modifies the original array by adding, removing, or substituting elements.
Q2. For what purpose is splice utilized?
The splice() method is employed to modify an array. You can use it to:
Remove elements from an array
Add new elements at any location.
Replace current elements with new ones.
Q3. For what scenarios is Splice optimal?
The splice() method is optimal for situations where you need to alter the structure of an array. The modifications are made to the current array.
Q4. How does the == operator differ from the === operator in JavaScript?
The == operator checks if two values are equal. It permits type conversion, meaning it will attempt to convert the values to the same type before comparing.
The === operator is the strict equality operator, implying it checks both the type and the value.
Q5. Does slice alter an array?
No, slice() doesn’t alter the original array. It returns a new array including selected elements.
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Comparison of Slice and Splice Methods in JavaScript – FAQs
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