How to fix Tuple type 'X' of length 2 has no element at index 3 in TypeScript

Look at the tuple definition near the error. If the type is declared as [string, number], the available indexes are only 0 and 1. The compiler shows the invalid index (3 in this message) so you know the tuple is too short for that access. Example:

const coords: [number, number] = [10, 20];
console.log(coords[3]); // ❌ Tuple type '[number, number]' of length 2 has no element at index 3

Find the tuple and index that triggered the message and confirm the size before proceeding.

Limit reads to indexes that exist. Use the first two positions or destructure the tuple so TypeScript can infer the values without an extra index:

const [x, y] = coords;
console.log(x, y); // ✅ uses indexes 0 and 1

Avoid writing coords[2] unless you have at least three entries in the type.

If your data now carries a third value (for example a label, flag, or optional metadata), add it to the tuple type and value:

const coords: [number, number, number] = [10, 20, 30];
console.log(coords[2]); // ✅ now index 2 exists

Updating the type keeps the runtime value in sync with what TypeScript expects.

When the number of entries can grow, prefer a regular array or a tuple with a rest element so the compiler knows you allow more values. For example:

type Measurements = [number, number, ...number[]];
const values: Measurements = [10, 20, 30, 40];
console.log(values[3]); // ✅ rest captures additional elements

This tells TypeScript the tuple starts with two fixed entries and can have more, so indexing past the first two is valid.

If you receive an index from user input or another function, check the tuple length before indexing:

function readAt<T extends unknown[]>(tuple: T, index: number) {
  if (index < tuple.length) {
    return tuple[index];
  }
  throw new Error('Index out of bounds');
}

Using tuple.length keeps the compiler happy while you safely handle long indexes in a single place.