Truncate a String in JavaScript

While working with the text, sometimes, there is a need to limit the number of characters of a string value. If the string values exceed the limit, trim the remaining part. Trimming or truncating is the process of cutting or eliminating parts of something to make it smaller. To trim or truncate a string, JavaScript has some predefined methods including the substring() method or the split() method with the join() method.

This tutorial will illustrate the methods to truncate a JavaScript string.

Truncate a String in JavaScript

To truncate a string, use the following methods:

substring() method
Combination of split() and join() method

Let’s explain these methods in detail.

Method 1: Truncate a String Using substring() Method

The substring() method is a “String” type method and it trims the string between the specified indexes. If the original string’s length exceeds the limit, it returns only that portion until the number of characters equals the specified limit:

Syntax
The given syntax is used for the “substring()” method:

substring(start, end)

It takes two parameters:

“start” is the start index of the substring
“end” is the last index where the string will be truncated.

Return Value: It will return a new trimmed string.

Example
First, create a variable “str1” that stores a string “Welcome to Linuxhint”:

var str1 = "Welcome to Linuxhint";

Define a function named “truncateString()” with two parameters, “string” and “limit”. In this function, check the length of the string using the “length” property. If the length of the string is greater than the specified limit, trim the string using the “substring()” method where the two arguments are passed, the start index of the string and the limit that will be the last index of the string:

function truncateString(string, limit){
if (string.length > limit){
str2 = string.substring(0,limit);
}
else{
return str1;
}
return str2;
}

Call the “truncateString()” function by passing string “str1” and limit “8”:

console.log(truncateString(str1, 8));

The output displays the trimmed string starting from the start index 0 and ending at the index 8:

Method 2: Truncate a String Using split() Method with join() Method

There is another method to truncate a string called the “split()” method which splits the string into an array of substrings on a specific character. To join the substrings into a string, use the “join()” method

Syntax
Follow the given syntax of the split() method for tokenizing a string in JavaScript:

split(separator, limit);

Here, the “separator” is any specific character that is used as the separator parameter to specify where to split the string.
“limit” is an integer that indicates the number of splits.
It returns an array of substrings based on the passed arguments.

Example
Utilize the same string “str1” created in the above example, and then, call the split() method by passing an empty string (‘’) and limit “11” as arguments:

var str = str1.split('', 11);

The output shows an array of substrings of length 11:

Now, join the array into a string using the join() method and store it in a variable “truncStr”:

var truncStr = str.join('');

Print the resultant string using the “console.log()” method:

console.log(truncStr);

Output

Conclusion

To truncate a string in JavaScript, use the “substring()” method, or the combination of the “split()” and “join()” methods. The substring() method is the most common method for truncating the strings in JavaScript. It trims the string between the specified indexes. The split() method splits the strings into an array of substrings and the join() method is used to convert that array of substrings to the string. This tutorial illustrated the methods for trimming JavaScript strings.

Truncate a String in JavaScript