HTML

Structure of content on the web

  • Web APIs

    Interfaces for building web applications

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  • JavaScript
  • Dynamic scripting with JavaScript
  • Grammar and types
  • Expressions and operators
  • Indexed collections
  • Using promises
  • JavaScript modules
  • Intermediate
    1. Language overview
    2. Closures
  • Advanced
    1. References
    2. ArrayBuffer
    3. AsyncIterator
    4. BigUint64Array
    5. decodeURI()
    6. Error
    7. escape()
    8. Float16Array
    9. Generator
    10. Int8Array
    11. InternalError
    12. Iterator
    13. NaN
    14. parseInt()
    15. ReferenceError
    16. SharedArrayBuffer
    17. Temporal
    18. Uint8ClampedArray
    19. unescape()
    20. WeakSet
  • Assignment (=)
  • Bitwise AND (&)
  • Bitwise OR assignment (|=)
  • Comma operator (,)
  • Destructuring
  • Exponentiation (**)
  • Greater than (>)
  • import.meta.resolve()
  • Inequality (!=)
  • Less than (<)
  • Logical NOT (!)
  • Multiplication assignment (*=)
  • Nullish coalescing assignment (??=)
  • Optional chaining (?.)
  • Right shift (>>)
  • Strict inequality (!==)
  • this
  • Unsigned right shift (>>>)
  • yield*
  • Block statement
  • continue
  • export
  • for...in
  • if...else
  • let
  • try...catch
  • with
  • get
  • The arguments object
    1. callee
    2. extends
    3. Static initialization blocks
  • Character class escape: \d, \D, \w, \W, \s, \S
  • Input boundary assertion: ^, $
  • Modifier: (?ims-ims:...)
  • Quantifier: *, +, ?, {n}, {n,}, {n,m}
  • Errors
    1. RangeError: argument is not a valid code point
    2. RangeError: invalid array length
    3. RangeError: repeat count must be less than infinity
    4. ReferenceError: assignment to undeclared variable "x"
    5. SyntaxError: 'arguments'/'eval' can't be defined or assigned to in strict mode code
    6. SyntaxError: \ at end of pattern
    7. SyntaxError: await is only valid in async functions, async generators and modules
    8. SyntaxError: continue must be inside loop
    9. SyntaxError: function statement requires a name
    10. SyntaxError: identifier starts immediately after numeric literal
    11. SyntaxError: invalid assignment left-hand side
    12. SyntaxError: invalid class set operation in regular expression
    13. SyntaxError: invalid property name in regular expression
    14. SyntaxError: invalid unicode escape in regular expression
    15. SyntaxError: missing ) after argument list
    16. SyntaxError: missing } after property list
    17. SyntaxError: missing variable name
    18. SyntaxError: numbers out of order in {} quantifier.
    19. SyntaxError: property name __proto__ appears more than once in object literal
    20. SyntaxError: rest parameter may not have a default
    21. SyntaxError: super() is only valid in derived class constructors
    22. SyntaxError: unlabeled break must be inside loop or switch
    23. TypeError: 'caller', 'callee', and 'arguments' properties may not be accessed
    24. TypeError: "x" is not a function
    25. TypeError: BigInt value can't be serialized in JSON
    26. TypeError: can't convert BigInt to number
    27. TypeError: can't redefine non-configurable property "x"
    28. TypeError: class constructors must be invoked with 'new'
    29. TypeError: Initializing an object twice is an error with private fields/methods
    30. TypeError: Iterator/AsyncIterator constructor can't be used directly
    31. TypeError: property "x" is non-configurable and can't be deleted
    32. TypeError: X.prototype.y called on incompatible type
    33. JavaScript technologies overview
    34. Strict mode
    35. JavaScript and gives an overview of the language. If you need exhaustive information about a language feature, have a look at the JavaScript reference.

      This Guide is divided into the following chapters.

    • Introduction

    Overview: Introduction

    Grammar and types

    Overview: Grammar and types

    Control flow and error handling

    Overview: Control flow and error handling

    Loops and iteration

    Overview: Loops and iteration

    Functions

    Overview: Functions

    Expressions and operators

    Overview: Expressions and operators

    Numbers and strings

    Overview: Numbers and strings

    Representing dates & times

    Overview: Representing dates & times

    Regular expressions

    Overview: Regular expressions

    Indexed collections

    Overview: Keyed collections

    Working with objects

    Overview: Working with objects

    Using classes

    Overview: Using classes

    Promises

    Overview: Promises

    Typed arrays

    Overview: Iterators and generators

    Internationalization

    Overview: Internationalization

    JavaScript modules

    Overview: JavaScript modules

    Advanced topics

    After you have learned all fundamental features of JavaScript, you can explore some more niche features, or dive deeper into the language's mechanisms and concepts.

    Our communities

    Visit Mozilla Corporation’s not-for-profit parent, the Mozilla Foundation.
    Portions of this content are ©1998–2025 by individual mozilla.org contributors. Content available under JavaScript reference.

    \n

    This Guide is divided into the following chapters.

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    1. JavaScript frameworks and libraries
  • Control flow and error handling
  • Numbers and strings
  • Keyed collections
  • JavaScript typed arrays
  • Advanced JavaScript objects
  • JavaScript data structures
  • Inheritance and the prototype chain
  • Built-in objects
    1. AsyncFunction
    2. Atomics
    3. Boolean
    4. decodeURIComponent()
    5. escape()\nDeprecated\n
    6. Float16Array
    7. Generator
    8. Int8Array
    9. Intl
    10. JSON
    11. Number
    12. Promise
    13. Reflect
    14. String
    15. TypedArray
    16. Uint16Array
    17. URIError
    18. Expressions & operators
      1. async function expression
      2. Bitwise AND assignment (&=)
      3. Bitwise XOR (^)
      4. Conditional (ternary) operator
      5. Division (/)
      6. Exponentiation assignment (**=)
      7. Greater than or equal (>=)
      8. import()
      9. instanceof
      10. Less than or equal (<=)
      11. Logical OR (||)
      12. new
      13. Nullish coalescing operator (??)
      14. Property accessors
      15. Right shift assignment (>>=)
      16. Subtraction (-)
      17. typeof
      18. Unsigned right shift assignment (>>>=)
      19. Statements & declarations
        1. break
        2. debugger
        3. Expression statement
        4. for...of
        5. import
          1. return
          2. var
          3. Arrow function expressions
          4. Rest parameters
          5. callee\nDeprecated\n
          6. extends
          7. Static initialization blocks
        6. Character class escape: \\d, \\D, \\w, \\W, \\s, \\S
        7. Input boundary assertion: ^, $
        8. Modifier: (?ims-ims:...)
        9. Quantifier: *, +, ?, {n}, {n,}, {n,m}
        10. Errors
          1. RangeError: argument is not a valid code point
          2. RangeError: invalid array length
          3. RangeError: repeat count must be less than infinity
          4. ReferenceError: assignment to undeclared variable \"x\"
          5. SyntaxError: 'arguments'/'eval' can't be defined or assigned to in strict mode code
          6. SyntaxError: \\ at end of pattern
          7. SyntaxError: await is only valid in async functions, async generators and modules
          8. SyntaxError: continue must be inside loop
          9. SyntaxError: function statement requires a name
          10. SyntaxError: identifier starts immediately after numeric literal
          11. SyntaxError: invalid assignment left-hand side
          12. SyntaxError: invalid class set operation in regular expression
          13. SyntaxError: invalid property name in regular expression
          14. SyntaxError: invalid unicode escape in regular expression
          15. SyntaxError: missing ) after argument list
          16. SyntaxError: missing } after property list
          17. SyntaxError: missing variable name
          18. SyntaxError: numbers out of order in {} quantifier.
          19. SyntaxError: property name __proto__ appears more than once in object literal
          20. SyntaxError: rest parameter may not have a default
          21. SyntaxError: super() is only valid in derived class constructors
          22. SyntaxError: unlabeled break must be inside loop or switch
          23. TypeError: 'caller', 'callee', and 'arguments' properties may not be accessed
          24. TypeError: \"x\" is not a function
          25. TypeError: BigInt value can't be serialized in JSON
          26. TypeError: can't convert BigInt to number
          27. TypeError: can't redefine non-configurable property \"x\"
          28. TypeError: class constructors must be invoked with 'new'
          29. TypeError: Initializing an object twice is an error with private fields/methods
          30. TypeError: Iterator/AsyncIterator constructor can't be used directly
          31. TypeError: property \"x\" is non-configurable and can't be deleted
          32. TypeError: X.prototype.y called on incompatible type
          33. JavaScript technologies overview
          34. Strict mode
          35. Deprecated features
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