In JavaScript, fold and reduce are functional programming techniques for aggregating data. The reduce() method iterates over an array and combines each element into a single result. It accepts a callback function with two parameters: accumulator (the accumulated value) and currentValue (the current element). The syntax is:
reduce() is useful for various tasks, such as summing numbers, flattening arrays, or accumulating objects. It represents a fold operation, combining elements into one value by applying a function to each item.
