Solved: truncate text

Truncating text is a common task in web development, especially when dealing with lengthy textual content that needs to fit within certain presentation limits without overloading the view. This usually happens in scenarios like news feeds, text previews, or indeed anywhere you might opt for a ‘read more’ type feature.

Approaching the Truncating Problem

To truncate text in JavaScript, there are a few different methods that we can use, either utilizing pure JavaScript or using libraries such as Lodash, each with its own approach and use case considerations.

Key in all these approaches is the substring() method. This method returns the part of the string between the start and end indexes, or to the end of the string.

let str = "Hello world!";
let res = str.substring(1, 4);

In this JavaScript code, we are creating a string that reads “Hello world!” and then using the substring method to return a section of it. In this case, res will be “ell”.

Step-By-Step Explanation

Let’s construct a JavaScript function to truncate a given piece of text to a specified length:

function truncateString(str, num) {
  if (str.length <= num) {
    return str
  return str.slice(0, num > 3 ? num - 3 : num) + '...'

Here’s how it works:

  • The function takes two parameters: the string, and the maximum length of the truncated string.
  • If the length of the string is less than or equal to the maximum length, the function will return the original string. This means that if our string is shorter than the length we want to truncate to, it will not be truncated at all.
  • If the string is longer, the function will slice it. If the maximum length is greater than 3, it will slice the string to the (length – 3) and then add ‘…’ at the end.

Use of Libraries

While native JavaScript functions provide a solid and quick solution to truncating text, there are also several libraries that you can use to achieve similar results.

One such library is Lodash, which includes a truncate function. Lodash’s truncate function is a bit more sophisticated, allowing you to specify the length of the truncation, the ending characters, and even maintain whole words.

_.truncate('this is some long text', {
  'length': 10,
  'separator': ' '
// => 'this is...'

In this example, Lodash’s truncate function is used to truncate a string after a certain number of characters, while ensuring that words aren’t cut in half. This opens up more options for customization and control over how your text is truncated.

Overall, truncating text in JavaScript can be accomplished through various means, each offering a different level of customization and complexity, and the method you choose ultimately depends on your project needs. The key thing is to remember that whatever method you choose, make sure it best fits the user experience and the overall layout and design of the web page.

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