Multiplication assignment (*=)

The multiplication assignment (*=) operator performs multiplication on the two operands and assigns the result to the left operand.

Try it

let a = 2;

console.log((a *= 3));
// Expected output: 6

console.log((a *= "hello"));
// Expected output: NaN

x *= y

x *= y is equivalent to x = x * y, except that the expression x is only evaluated once.

undefined

let bar = 5;
bar *= 2; // 10

Other non-BigInt values are coerced to numbers:

let bar = 5;
bar *= "foo"; // NaN

let foo = 3n;
foo *= 2n; // 6n
foo *= 1; // TypeError: Cannot mix BigInt and other types, use explicit conversions