JavaScript - Remove first n characters from string

In JavaScript, removing the first n characters from a string is a common operation when processing text data. There are several efficient methods to accomplish this task.

What is String Character Removal?

Removing the first n characters from a string means creating a new string that excludes the specified number of characters from the beginning.

For example

Input ?

const str = "JavaScript";
const n = 4;

Output ?

Script

Different Approaches

The following are the different approaches to remove the first n characters from a string in JavaScript ?

• Using slice() Method
• Using substring() Method
• Using substr() Method

Using slice() Method

The slice() method extracts a section of a string and returns it as a new string. By passing the starting index as n, we can remove the first n characters.

Following are the steps to remove first n characters using slice() ?

• Call slice(n): Starting from index n to the end of the string.
• Return new string: The original string remains unchanged.

Syntax

string.slice(startIndex, endIndex)

Example

const removeFirstNChars = (str, n) => {
    return str.slice(n);
};

const originalString = "JavaScript Programming";
console.log("Original string:", originalString);
console.log("Remove first 4 characters:", removeFirstNChars(originalString, 4));
console.log("Remove first 10 characters:", removeFirstNChars(originalString, 10));

Original string: JavaScript Programming
Remove first 4 characters: Script Programming
Remove first 10 characters:  Programming

Using substring() Method

The substring() method returns the part of the string between the start and end indexes. When called with only the start parameter, it returns from that index to the end.

Example

const removeWithSubstring = (str, n) => {
    return str.substring(n);
};

const text = "Hello World!";
console.log("Original:", text);
console.log("Remove first 6 characters:", removeWithSubstring(text, 6));
console.log("Remove first 2 characters:", removeWithSubstring(text, 2));

Original: Hello World!
Remove first 6 characters: World!
Remove first 2 characters: llo World!

Using substr() Method

The substr() method returns a portion of the string, starting at the specified index. Note that this method is deprecated but still widely supported.

Example

const removeWithSubstr = (str, n) => {
    return str.substr(n);
};

const phrase = "TutorialsPoint";
console.log("Original:", phrase);
console.log("Remove first 9 characters:", removeWithSubstr(phrase, 9));
console.log("Remove first 3 characters:", removeWithSubstr(phrase, 3));

Original: TutorialsPoint
Remove first 9 characters: Point
Remove first 3 characters: orialsPoint

Comparison

Edge Cases

const handleEdgeCases = (str, n) => {
    if (n = str.length) return "";
    return str.slice(n);
};

console.log("Empty string:", handleEdgeCases("", 2));
console.log("n = 0:", handleEdgeCases("test", 0));
console.log("n > length:", handleEdgeCases("hi", 5));

n = 0: test
n > length: 

Conclusion

The slice() method is the most recommended approach for removing the first n characters from a string. It's widely supported, efficient, and handles edge cases gracefully. Avoid using substr() as it's deprecated in modern JavaScript.