How to trim a String to N characters in JavaScript

Trim a String to N characters in JavaScript #

To trim a string to N characters, use the substring() method, passing it a starting index of 0 and an end index of the desired string length. The substring method returns the part of the string between the start and end indexes.

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const str = 'Hello World Goodbye World';

const length = 11;

const trimmed = str.substring(0, length);
console.log(trimmed); // 👉️ Hello World

We used the String.substring method to trim a string to 11 characters.

The parameters we passed to the method are:

1. the start index - the index of the first character to be included in the returned string
2. the end index - go up to, but not including this index

If you need to add ellipsis to the truncated string in case there are remaining characters, you can use a ternary operator.

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const str = 'Hello World Goodbye World';

const length = 11;

const trimmed =
  str.length > length
    ? str.substring(0, length) + '...'
    : str.substring(0, length);

console.log(trimmed); // 👉️ Hello World...

The ternary operator is very similar to an if / else statement.

We first check if the string's length is greater than how many characters we want to trim off the string. If it is, we have to add ellipsis.

The code snippet above is equivalent to the following if/else statement.

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const str = 'Hello World Goodbye World';

const length = 11;

let trimmed;

if (str.length > length) {
  trimmed = str.substring(0, length) + '...';
} else {
  trimmed = str.substring(0, length);
}

console.log(trimmed) // 👉️ Hello World...

Definitely not elegant as the ternary operator, however it's easier to read if you're not used to the syntax.

Further Reading #

• Remove all Spaces from a String in JavaScript
• Replace all Numbers in a String using JavaScript
• Remove all Numbers from a String in JavaScript
• Remove Empty Strings from an Array in JavaScript
• Remove Empty String Values from an Object in JavaScript
• How to compare Strings in JavaScript
• How to get the Length of a String in JavaScript
• Check if Array contains Empty String in JavaScript
• Interpolate Variable in a String in JavaScript
• Check if letter in String is Uppercase or Lowercase in JS
• Check if String contains only Letters and Spaces in JS
• Check if String contains only Letters and Numbers in JS
• Remove all non-alphanumeric Characters from String in JS