JavaScript:
Extracting substrings

How to:

Using substring method:

let text = "JavaScript is awesome!";
let extracted = text.substring(0, 10);
console.log(extracted); // Output: JavaScript

Using slice method:

let text = "JavaScript is awesome!";
let sliced = text.slice(-9, -1);
console.log(sliced); // Output: awesome

Using substr method (deprecated):

let text = "JavaScript is awesome!";
let substrd = text.substr(11, 7);
console.log(substrd); // Output: awesome

Deep Dive

Extracting substrings isn’t new – it’s as old as programming itself. The substring and slice methods in JavaScript are tools from the 1990s, part of the language’s initial feature set. substr was also in there, but it’s now legacy code and should be avoided in modern applications.

The difference? substring and slice are similar – both take start and end index parameters – but handle negatives differently: slice can handle negative indices, counting from the end, while substring treats them as zeroes. All these methods don’t mutate the original string; they produce new ones.

See Also

• Mozilla Developer Network on Strings: MDN Web Docs - String
• String manipulation with JavaScript: W3Schools - JavaScript String Methods
• JavaScript string basics: JavaScript.info - Strings