String.prototype.substring() — JS Technical Interview Questions & Answers

Extracts characters between two indices.

String.prototype.substring()

  • String.prototype.substring() is a JS topic. In plain words you use it for class Student in a tiny OOP file. Don’t start with a slogan — start with that picture.
  • Smallest example: class Student { constructor(name) {} }. Type it, run it, and say what you see. If you can do that from memory, you know String.prototype.substring().
  • From the example next to this theory: Extracts characters between two indices.
  • Trap: arrow function for a method that needs this. Fix that before you talk about advanced JS.
  • Viva: what is String.prototype.substring()? Then show class Student { constructor(name) {} }. Then name the trap.

Technical Interview Tip: What is String.prototype.substring()? Show this: class Student { constructor(name) {} }. Trap: arrow function for a method that needs this.

Code Examples for String.prototype.substring()

String.prototype.substring() — working example

// Topic: String.prototype.substring()
const nums = [1, 2, 3];
const doubled = nums.map((n) => n * 2);
console.log(doubled);
console.log(doubled.reduce((a, b) => a + b, 0));

String.prototype.substring(): map then reduce on [1, 2, 3]. Say both prints.

How to Explain String.prototype.substring() to an Interviewer

What is String.prototype.substring()?

Used for class Student a tiny OOP file Not just the heading

Give one small example of String.prototype.substring().

class Student { constructor(name) {} } Extracts characters between two indices

What mistake do beginners make with String.prototype.substring()?

arrow function for a method that needs this Show the fix

Where do you use String.prototype.substring()?

a tiny OOP file class Student