The exponentiation assignment (**=) operator performs exponentiation on the two operands and assigns the result to the left operand.
Syntax
x **= y
Description
x **= y is equivalent to x = x ** y, except that the expression x is only evaluated once.
Examples
Using exponentiation assignment
let bar = 5;
bar **= 2; // 25
bar **= "foo"; // NaN
let foo = 3n;
foo **= 2n; // 9n