Bit flags
Testing whether a flag bit is set in a compact bit mask.
JS Puzzles · Const
Bitwise Tricks
JavaScript bitwise operators manipulate the binary representation of 32-bit integer operands. They include logical bit operations and left or right shifts, and are mainly useful for specialized low-level tasks.
How it works
JavaScript bitwise operators convert numeric operands to 32-bit integers and apply the operation to their binary representations. AND, OR, XOR, and NOT manipulate corresponding bits, while shift operators move bits left or right; the result is an ordinary JavaScript number.
Syntax
a & b; a | b; a ^ b; ~a; a << b; a >> b; a >>> bReturns
Each operator produces a JavaScript number resulting from its bitwise operation.
Key points
- Bitwise operators work on 32-bit integer representations rather than directly on decimal values.
- The available operators are AND (&), OR (|), XOR (^), NOT (~), left shift (<<), right shift (>>), and zero-fill right shift (>>>).
- The same family of bitwise operators is common across many programming languages.
- Bitwise syntax and concepts are broadly shared, which can help when translating low-level algorithms between languages.
- Bitwise operations can be appropriate in specialized areas such as cryptography.
Common mistakes
- Operands are handled as 32-bit integers, so bitwise operations are unsuitable when preserving arbitrary-precision numeric values matters.
Example: Basic bitwise operations
const flags = 0b1010;
const read = 0b0010;
console.log((flags & read) !== 0); // true
console.log(flags ^ read); // 8
console.log(flags << 1); // 20
This runnable example checks a bit with AND, combines differences with XOR, and shifts bits left.
When to use it
Packed options
Combining or removing compact binary options.
Low-level algorithms
Implementing specialized low-level numeric or cryptographic algorithms.
Related
operatorsnumbersbinary representationAND (&)OR (|)XOR (^)NOT (~)LEFT SHIFT (<<)