# Built-in methods {#js_builtin}

## require()
Load a module plugin.

**Parameters**
- Module name

**Examples**
```js
let serial = require("serial"); // Load "serial" module
```

<br>

## delay()
**Parameters**
- Delay value in ms

**Examples**
```js
delay(500); // Delay for 500ms
```
<br>

## print()
Print a message on a screen console.

**Parameters**
The following argument types are supported:
- String
- Number
- Bool
- undefined

**Examples**
```js
print("string1", "string2", 123);
```
<br>

## console.log()

<br>

## console.warn()

<br>

## console.error()

<br>

## console.debug()
Same as `print`, but output to serial console only, with corresponding log level.

<br>

## to_string()
Convert a number to string with an optional base.

**Examples**
```js
to_string(123) // "123"
to_string(123, 16) // "0x7b"
```