eval AND ARGUMENTS

Strict mode now explicitly disallows using eval and arguments as identifiers and manipulating their values. For example:

// Redefining eval and arguments as variables
// Non-strict mode: Okay, no error.
// Strict-mode: Throws syntax error
let eval = 10;
let arguments = "Hello world!";

In nonstrict mode, you can overwrite eval and assign arguments to a value. In strict mode, this causes a syntax error. You can't use either as an identifier, which means all of the following use cases throw a syntax error:

• Declaration using let
• Assignment to another value
• Attempts to change the contained value, such as using ++
• Used as function names
• Used as named function arguments
• Used as exception name in try-catch statement