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Practice

Identifiers and Literals

Identifier and Literal are important concepts in programming languages, used to name variables, constants, functions, etc., or to represent the values themselves.


Identifier​

  • Definition: An identifier is a name used to distinguish variables, functions, objects, etc.
  • Example: In let appleCount = 5; appleCount is the identifier.
  • Rules:
    • An identifier can start with an alphabet, dollar sign ($), or underscore (_).
    • From the second character, an identifier can also include numbers.
    • Reserved keywords cannot be used as identifiers (e.g., let, if, etc.).

Literal​

  • Definition: A literal is a fixed value directly written in the source code. Literals are used as they are when assigned to a variable or used in operations.
  • Example: In let appleCount = 5; 5 is a numeric literal.
  • Types:
    • Numeric literals: e.g., 123, 3.14
    • String literals: e.g., "hello", 'world'
    • Boolean literals: e.g., true, false
    • Object literals: e.g., {name: "John", age: 30}
    • Array literals: e.g., [1, 2, 3]
    • Regular expression literals: e.g., /ab+c/

In short, an identifier is a name used to refer to or call upon data or functions, while a literal is a fixed value used directly in the code.

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