But for me, the trick was to understand that the result of each run of the callback function will be stored in the first argument it takes, this little a or accumulator. If used postfix, with operator after operand (for example, x- ), the decrement operator.
It performs BigInt decrement if the operand becomes a BigInt otherwise, it performs number decrement. It first coerces the operand to a numeric value and tests the type of it. It can be a bit confusing at the beginning. reduce() method combines each element of an array, using a specified reducer function, and returns a single value. The - operator is overloaded for two types of operands: number and BigInt.
Reduce() is a powerful method that can be used to transform data in an array in many ways.
