What are the differences between JavaScript's String.slice() and String.substring() methods?
Richard W

JavaScript provides two methods,slice() andsubstring(), for extracting parts of a string. While they are similar in functionality, there are some differences between them. Here's a detailed comparison ofslice() andsubstring(): 1. Parameter handling: -slice(startIndex, endIndex): - Allows both positive and negative indices. -startIndex is inclusive, andendIndex is exclusive. - IfstartIndex is negative, it counts from the end of the string. - IfendIndex is omitted, it extracts until the end of the string. -substring(startIndex, endIndex): - Only allows positive indices. - BothstartIndex andendIndex are inclusive. - IfstartIndex is greater thanendIndex, the parameters are swapped. 2. Negative indices: -slice(): - Supports negative indices. - Negative indices are relative to the end of the string. -substring(): - Does not support negative indices. - If negative indices are provided, they are treated as zero. 3. Returning the substring: -slice() andsubstring() return a new string that contains the extracted substring. - The original string is not modified. 4. Handling out-of-range indices: -slice(): - IfstartIndex is greater than the string length, an empty string is returned. - IfendIndex is greater than the string length, it extracts until the end of the string. -substring(): - If eitherstartIndex orendIndex is greater than the string length, they are treated as the string length. 5. String reversal: -slice(): - Can be used with negative indices to reverse a string. -substring(): - Cannot be directly used for string reversal since it doesn't support negative indices. Here are some examples illustrating the differences:

1
2
3
4
5
6
7
8
9
10
11
12
13
14

const str = "Hello, World!";

console.log(str.slice(7, 12)); // Output: "World"
console.log(str.slice(-6)); // Output: "World!"

console.log(str.substring(7, 12)); // Output: "World"
console.log(str.substring(-6)); // Output: "Hello, World!"

console.log(str.slice(12, 7)); // Output: ""
console.log(str.substring(12, 7)); // Output: "World"

console.log(str.slice(7)); // Output: "World!"
console.log(str.substring(7)); // Output: "World!"

In summary,slice() andsubstring() are similar in functionality, but they differ in how they handle negative indices, out-of-range indices, and the inclusiveness of the specified indices. Consider the specific requirements of your use case and choose the method that best suits your needs.

Similar Questions