Suggest an edit

Improve this article

Refine the answer for “Primitive types”. Your changes go to moderation before they’re published.

Approval required

Content

What you’re changing

Title (EN)

Short answer (EN)

Shown above the full answer for quick recall.

Answer (EN)

TypeScript has several **primitive types**, which are the basic building blocks of the language (that is, not objects and with no methods except the built-in ones via the prototype).
Here is the full list:

---

### Main primitive types

1. `string` - a string
Used for text data.

```javascript
  let name: string = "Tim";
  ```
2. `number` - a number
Covers both integer and fractional values (all numbers are floating-point).

```javascript
  let age: number = 25;
  let price: number = 19.99;
  ```
3. `boolean` - a boolean value (true/false)

```javascript
  let isOnline: boolean = true;
  ```
4. `bigint` - an integer of arbitrary length (ES2020+)
Used when you need to work with very large numbers.

```javascript
  let big: bigint = 123456789012345678901234567890n;
  ```
5. `symbol` - a unique identifier (ES2015+)
Guarantees the uniqueness of a value, often used as an object key.

```javascript
  const id: symbol = Symbol("id");
  ```
6. `undefined` - the "not defined" value
Usually means that a variable is declared but has no value.

```javascript
  let value: undefined = undefined;
  ```
7. `null` - the intentional absence of a value

```javascript
  let empty: null = null;
  ```

---

### Special (not quite primitive, but closely related)

8. `void` - "returns nothing"
Used as the type of a function that returns no value.

```javascript
  function logMessage(): void {
    console.log("Hello");
  }
  ```
9. `never` - "never happens"
Used for functions that **never complete successfully** (for example, they throw an error or loop forever).

```javascript
  function fail(): never {
    throw new Error("Error!");
  }
  ```
10. `unknown` - an "unknown type"
A safe alternative to `any`. Requires a check before use.

```javascript
  let data: unknown = "Hello";
  if (typeof data === "string") {
    console.log(data.toUpperCase());
  }
  ```
11. `any` - "any type"
Turns off type checking (used rarely and carefully).

```javascript
  let something: any = 123;
  something = "text"; // allowed
  ```

---

### Summary:

| Category | Types |
|---|---|
| Primitive | `string`, `number`, `boolean`, `bigint`, `symbol`, `null`, `undefined` |
| Special utility | `void`, `never`, `unknown`, `any` |

Markdown · drag & drop images · ⌘B / ⌘I shortcuts338 words

For the reviewer

Note to the moderator (optional)

Visible only to the moderator. Helps review go faster.