Exponentiation (**)

The exponentiation operator is right-associative: a ** b ** c is equal to a ** (b ** c).

In most languages, such as PHP, Python, and others that have an exponentiation operator (**), the exponentiation operator is defined to have a higher precedence than unary operators, such as unary + and unary -, but there are a few exceptions. For example, in Bash, the ** operator is defined to have a lower precedence than unary operators.

In JavaScript, it is impossible to write an ambiguous exponentiation expression. That is, you cannot put a unary operator (+/-/~/!/delete/void/typeof) immediately before the base number; doing so will cause a SyntaxError.

For example, -2 ** 2 is 4 in Bash, but is -4 in other languages (such as Python). This is invalid in JavaScript, as the operation is ambiguous. You have to parenthesize either side — for example, as -(2 ** 2) — to make the intention unambiguous.

Note that some programming languages use the caret symbol ^ for exponentiation, but JavaScript uses that symbol for the bitwise logical XOR operator.

NaN ** 0 (and the equivalent Math.pow(NaN, 0)) is the only case where NaN doesn't propagate through mathematical operations — it returns 1 despite the operand being NaN. In addition, the behavior where base is 1 and exponent is non-finite (±Infinity or NaN) is different from IEEE 754, which specifies that the result should be 1, whereas JavaScript returns NaN to preserve backward compatibility with its original behavior.

To invert the sign of the result of an exponentiation expression:

-(2 ** 2); // -4

To force the base of an exponentiation expression to be a negative number:

(-2) ** 2; // 4

• Addition operator
• Subtraction operator
• Division operator
• Multiplication operator
• Remainder operator
• Increment operator
• Decrement operator
• Unary negation operator
• Unary plus operator