JavaScript has many built-in functions that are available to use in your code. These functions are part of the JavaScript standard library and provide a wide range of useful utilities for working with numbers, strings, arrays, objects, and other data types.

Here are a few examples of built-in JavaScript functions:

• Math.abs(): This function returns the absolute value of a number. For example: Math.abs(-5) returns 5.
• Math.max(): This function returns the maximum value of a list of numbers. For example: Math.max(1, 2, 3, 4, 5) returns 5.
• Math.min(): This function returns the minimum value of a list of numbers. For example: Math.min(1, 2, 3, 4, 5) returns 1.
• String.prototype.toUpperCase(): This function converts a string to uppercase. For example: "hello".toUpperCase() returns "HELLO".
• String.prototype.toLowerCase(): This function converts a string to lowercase. For example: "HELLO".toLowerCase() returns "hello".
• Array.prototype.push(): This function adds one or more elements to the end of an array. For example: [1, 2, 3].push(4, 5) returns [1, 2, 3, 4, 5].
• Array.prototype.pop(): This function removes the last element from an array and returns it. For example: [1, 2, 3].pop() returns 3.

These are just a few examples of the many built-in functions that are available in JavaScript. You can find a complete list of these functions in the JavaScript documentation.

Here is a link to the JavaScript documentation on MDN Web Docs:

https://developer.mozilla.org/en-US/docs/Web/JavaScript

You can use this link to access the documentation and browse the available functions.

I hope this helps! Let me know if you have any other questions.