To remove the last character from a string in JavaScript, there are multiple approaches with varying use cases and nuances. Below is a detailed breakdown with examples, edge-case handling, and performance considerations.
1. Using slice() (Most Recommended)
The slice() method extracts a section of a string and returns it as a new string.
Syntax:
string.slice(startIndex, endIndex);Example 1: Basic Usage
const str = "Hello World!";
const trimmed = str.slice(0, -1); // "Hello World"Example 2: Handling Edge Cases
const emptyStr = "";
const singleChar = "A";
console.log(emptyStr.slice(0, -1)); // "" (no change)
console.log(singleChar.slice(0, -1)); // ""2. Using substring()
The substring() method returns part of the string between start and end indices.
Syntax:
string.substring(startIndex, endIndex);Example 1: Basic Usage
const str = "12345";
const trimmed = str.substring(0, str.length - 1); // "1234"Example 2: With Dynamic Values
const filename = "image.jpg";
const basename = filename.substring(0, filename.length - 4); // "image"3. Using substr() (Legacy Method ⚠️)
Deprecated but still functional, substr() takes a start index and length.
Syntax:
string.substr(startIndex, length);const str = "abcde";
const trimmed = str.substr(0, str.length - 1); // "abcd"4. Convert to Array and Modify
Split the string into an array, remove the last character, and rejoin it.
Use Case: Useful for complex manipulations (e.g., conditional removal).
Example 1: Using pop()
const str = "apple";
const arr = str.split(''); // ["a", "p", "p", "l", "e"]
arr.pop(); // Remove last element
const trimmed = arr.join(''); // "appl"Example 2: Using slice() on Arrays
const str = "test";
const trimmed = str.split('').slice(0, -1).join(''); // "tes"5. Trim Whitespace Only
To remove trailing whitespace (not just any character), use trimEnd():
const str = "Text ";
const trimmed = str.trimEnd(); // "Text"Edge Cases & Validation
Always validate the string length to avoid errors with empty strings:
function safeTrimLastChar(str) {
return str.length > 0 ? str.slice(0, -1) : str;
}
console.log(safeTrimLastChar("")); // ""
console.log(safeTrimLastChar("a")); // ""
console.log(safeTrimLastChar("abc")); // "ab"Performance Comparison
| Method | Speed (Relative) | Notes |
|---|---|---|
slice() | 🚀 Fastest | Clean syntax, handles negative indices |
substring() | 🚀 Fast | Explicit indices, no negative values |
substr() | ⚠️ Deprecated | Avoid for new code |
Array (split/pop) | 🐢 Slowest | Useful for complex logic |
Advanced Use Cases
1. Remove Last Character Conditionally
Only remove the last character if it matches a specific value:
const str = "Hello!";
const trimmed = str.endsWith("!") ? str.slice(0, -1) : str; // "Hello"2. Remove Last N Characters
Generalize the logic to trim the last N characters:
const removeLastN = (str, n) => str.slice(0, -n);
console.log(removeLastN("abcdef", 3)); // "abc"3. Remove Trailing Slashes in URLs
Trim trailing / from URLs:
const url = "https://example.com/path/";
const cleanUrl = url.replace(/\/$/, ""); // "https://example.com/path"Summary
- For Most Cases: Use
str.slice(0, -1)for simplicity and performance. - Validation: Check for empty strings if necessary.
- Specialized Trimming: Use regex or conditional logic for non-generic cases.