The String object's slice() method

The String object's slice() method extracts a portion of a string and returns it as a new string, without modifying the original string.

Syntax

string.slice(startIndex[, endIndex])

Parameters

startIndex:

• The index at which to begin extraction. The first character is at index 0.

• If negative, it is treated as str.length + startIndex. For example, if startIndex is -3, it is treated as str.length - 3.

endIndex (optional):

• The index at which to end extraction. The character at this index will not be included.

• If omitted, slice() extracts through the end of the string.

• If negative, it is treated as str.length + endIndex.

Return value

The slice() method returns a new string containing the extracted section of the string.

Examples

Example 1: Basic string slicing with positive indices

In the code below, the function sliceEx1() demonstrates basic string slicing operations.

function sliceEx1() {
  let str = "Hello World!";
  
  // Extract "Hello" (characters from index 0 to 4)
  Logger.log(str.slice(0, 5));
  
  // Extract "World" (characters from index 6 to 10)
  Logger.log(str.slice(6, 11));
  
  // Extract from index 6 to the end
  Logger.log(str.slice(6));
}

Output

Hello

World

World!

Example 2: String slicing with negative indices

In the code below, the function sliceEx2() shows how negative indices work with slice().

function sliceEx2() {
  let str = "Hello World!";
  
  // Extract last 6 characters
  Logger.log(str.slice(-6));
  
  // Extract "World" using negative indices
  Logger.log(str.slice(-6, -1));
  
  // Extract everything except last character
  Logger.log(str.slice(0, -1));
}

Output

World!

World

Hello World

Example 3: Common use cases for slice()

In the code below, the function sliceEx3() demonstrates practical applications of the slice() method.

function sliceEx3() {
  // Truncate long text
  let longText = "This is a very long string that needs to be truncated";
  let truncated = longText.slice(0, 20) + "...";
  Logger.log(truncated);
  
  // Extract domain from email
  let email = "user@example.com";
  let domain = email.slice(email.indexOf("@") + 1);
  Logger.log(domain);
  
  // Extract file extension
  let filename = "document.pdf";
  let extension = filename.slice(filename.lastIndexOf("."));
  Logger.log(extension);
}

Output

This is a very long…

example.com

.pdf

Example 4: Demonstrating that slice() returns a new string

In the code below, the function sliceEx4() shows how slice() creates a new string without modifying the original.

function sliceEx4() {
  let originalStr = "Hello World!";
  
  // Create a new string using slice()
  let slicedStr = originalStr.slice(0, 5);
  
  // Log both strings to show original is unchanged
  Logger.log("Original string: " + originalStr);
  Logger.log("Sliced string: " + slicedStr);
  
  // Prove they are separate strings
  let slicedStr2 = slicedStr.toUpperCase();
  Logger.log("Modified sliced string: " + slicedStr2);
  Logger.log("Original string still unchanged: " + originalStr);
}

Output

Original string: Hello World!

Sliced string: Hello

Modified sliced string: HELLO

Original string still unchanged: Hello World!

function sliceNote() {
  let str = "Hello World!";
  Logger.log(str.slice(5, 1)); // Returns empty string
}

Conclusion

In this tutorial, you learned how to use the slice() method to extract portions of strings in Apps Script. The slice() method is particularly useful for text processing tasks like truncation, extraction of substrings, and working with file names or email addresses.