Identifiers and Literals
Identifiers and Literals are important concepts in programming languages, used to name variables, constants, functions, and to represent fixed values in the code.
Identifier
- Definition: An identifier is a name used to identify variables, functions, objects, etc.
- Example: In
let appleCount = 5;,appleCountis an identifier. - Rules:
- Identifiers can start with a letter, a dollar sign (
$), or an underscore (_). - Subsequent characters can also be digits.
- Reserved words cannot be used as identifiers. (e.g.,
let,if, etc.)
- Identifiers can start with a letter, a dollar sign (
Literal
- Definition: A literal is a fixed value that appears directly in the source code. It is used exactly as it is when assigned to a variable or used in an operation.
- Example: In
let appleCount = 5;,5is a numeric literal. - Types:
- Numeric literal: e.g.,
123,3.14 - String literal: e.g.,
"hello",'world' - Boolean literal: e.g.,
true,false - Object literal: e.g.,
{name: "John", age: 30} - Array literal: e.g.,
[1, 2, 3] - Regular expression literal: e.g.,
/ab+c/
- Numeric literal: e.g.,
In short, an identifier is a name used to reference or call data or functions, while a literal is a fixed value directly used in the code.
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