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Dcalage binaire gauche (<<)

Baseline Large disponibilit

Cette fonctionnalit est bien tablie et fonctionne sur de nombreux appareils et versions de navigateurs. Elle est disponible sur tous les navigateurs depuis juillet 2015.

L'oprateur de dcalage binaire gauche (<<) dcale la squence de bits reprsente par le premier oprande d'autant de bits vers la gauche que le nombre indiqu par le second oprande. Les bits en excs gauche sont carts et des bits zro sont introduits droite.

Dans cet article

Exemple interactif

const a = 5; // 00000000000000000000000000000101
const b = 2; // 00000000000000000000000000000010

console.log(a << b); // 00000000000000000000000000010100
// Expected output: 20

Syntaxe

js
a << b;

Description

Cet oprateur dcale les bits du premier oprande vers la gauche, d'autant que le nombre indiqu par le second oprande. Les bits qui dpassent gauche sont abandonns et des zros sont introduits droite.

Ainsi, 9 << 2 donnera la valeur 36 (en base 10) :

js
       9 (base 10): 00000000000000000000000000001001 (base 2)
                    --------------------------------
  9 << 2 (base 10): 00000000000000000000000000100100 (base 2) = 36 (base 10)

Le dcalage binaire de tout nombre x de y bits vers la gauche donnera comme rsultat x * 2 ** y. Par exemple, 9 << 3 pourra tre reformul en 9 * (2 ** 3) = 9 * (8) = 72.

Exemples

Utiliser le dcalage binaire gauche

js
9 << 3; // 72

// 9 * (2 ** 3) = 9 * (8) = 72

Spcifications

Spcification
ECMAScript 2027 LanguageSpecification
# sec-left-shift-operator

Compatibilit des navigateurs

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  1. JavaScript
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  3. Guide JavaScript
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    2. Types et grammaire
    3. Contrle du flux et gestion des erreurs
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  5. Avanc
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  7. Objets natifs
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  8. Expressions et oprateurs
    1. Addition (+)
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    3. Assignement (=)
    4. Expression async function
    5. Expression async function*
    6. await
    7. ET binaire (&)
    8. Affectation aprs ET binaire (&=)
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    11. Affectation aprs OU binaire (|=)
    12. OU exclusif binaire (^)
    13. Affectation aprs OU exclusif binaire (^=)
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    31. import
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    35. instanceof
    36. Dcalage binaire gauche (<<)
    37. Affectation aprs dcalage gauche (<<=)
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    56. Reste (%)
    57. Affectation aprs reste (%=)
    58. Dcalage binaire droite (>>)
    59. Affectation aprs dcalage droite (>>=)
    60. Syntaxe de dcomposition
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    65. super
    66. L'oprateur this
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    70. Dcalage binaire droite non-sign (>>>)
    71. Affectation aprs dcalage droite non sign (>>>=)
    72. L'oprateur void
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  9. Instructions et dclarations
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    35. SyntaxError: for-in loop head declarations may not have initializers
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    38. SyntaxError: getter and setter for private name #x should either be both static or non-static
    39. SyntaxError: getter functions must have no arguments
    40. SyntaxError: identifier starts immediately after numeric literal
    41. SyntaxError: illegal character
    42. SyntaxError: import declarations may only appear at top level of a module
    43. SyntaxError: incomplete quantifier in regular expression
    44. ReferenceError: invalid assignment left-hand side
    45. SyntaxError: invalid BigInt syntax
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    47. SyntaxError: invalid character in class in regular expression
    48. SyntaxError: invalid class set operation in regular expression
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    54. SyntaxError: invalid regexp group
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    56. SyntaxError: invalid unicode escape in regular expression
    57. SyntaxError: JSON.parse: bad parsing
    58. SyntaxError: label not found
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    60. SyntaxError: missing ) after argument list
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    62. SyntaxError: missing ] after element list
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    66. SyntaxError: missing formal parameter
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    80. SyntaxError: rest parameter may not have a default
    81. SyntaxError: return not in function
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    83. SyntaxError: unterminated string literal
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    85. SyntaxError: tagged template cannot be used with optional chain
    86. SyntaxError: Unexpected '#' used outside of class body
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    88. SyntaxError: unlabeled break must be inside loop or switch
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    91. SyntaxError: Using //@ to indicate sourceURL pragmas is deprecated. Use //# instead
    92. ReferenceError: deprecated caller or arguments usage
    93. TypeError: 'x' is not iterable
    94. TypeError: "x" is (not) "y"
    95. TypeError: "x" is not a constructor
    96. TypeError: "x" is not a function
    97. TypeError: "x" is not a non-null object
    98. TypeError: "x" is read-only
    99. TypeError: already executing generator
    100. TypeError: BigInt value can't be serialized in JSON
    101. TypeError: calling a builtin X constructor without new is forbidden
    102. TypeError: can't access/set private field or method: object is not the right class
    103. TypeError: can't assign to property "x" on "y": not an object
    104. TypeError: can't convert BigInt to number
    105. TypeError: can't convert x to BigInt
    106. TypeError: can't define property "x": "obj" is not extensible
    107. TypeError: can't delete non-configurable array element
    108. TypeError: can't redefine non-configurable property "x"
    109. TypeError: can't set prototype of this object
    110. TypeError: can't set prototype: it would cause a prototype chain cycle
    111. TypeError: invalid 'in' operand "x"
    112. TypeError: class constructors must be invoked with 'new'
    113. TypeError: cyclic object value
    114. TypeError: derived class constructor returned invalid value x
    115. TypeError: getting private setter-only property
    116. TypeError: Initializing an object twice is an error with private fields/methods
    117. TypeError: invalid 'instanceof' operand 'x'
    118. TypeError: invalid Array.prototype.sort argument
    119. TypeError: invalid assignment to const "x"
    120. TypeError: Iterator/AsyncIterator constructor can't be used directly
    121. TypeError: matchAll/replaceAll must be called with a global RegExp
    122. TypeError: More arguments needed
    123. TypeError: "x" has no properties
    124. TypeError: property "x" is non-configurable and can't be deleted
    125. TypeError: Reduce of empty array with no initial value
    126. TypeError: setting a property that has only a getter
    127. TypeError: WeakSet key/WeakMap value 'x' must be an object or an unregistered symbol
    128. TypeError: X.prototype.y called on incompatible type
    129. URIError: malformed URI sequence
    130. Warning: -file- is being assigned a //# sourceMappingURL, but already has one
    131. Warning: unreachable code after return statement
  14. Divers
    1. Aperu des technologies JavaScript
    2. Modle d'excution
    3. Grammaire lexicale
    4. Protocoles d'itration
    5. Mode strict
    6. Gabarits de chanes de caractres
    7. Virgules finales
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