Aggregate

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Applies an accumulator function over a sequence. The specified seed value is used as the initial accumulator value, and the specified function is used to select the result value.

Syntax

Aggregate([seed,] func[, resultSelector])

Parameters

seed

The initial accumulator value.

func

An accumulator function to be invoked on each element. TAccumulate func(TAccumulate, TSource)

resultSelector

A function to transform the final accumulator value into the result value. TResult resultSelector(TAccumulate)

Return Value

The transformed final accumulator value.

Remarks

The Aggregate method makes it simple to perform a calculation over a sequence of values. This method works by calling func one time for each element in source. Each time func is called, Aggregate passes both the element from the sequence and an aggregated value (as the first argument to func). The value of the seed parameter is used as the initial aggregate value. The result of func replaces the previous aggregated value. The final result of func is passed to resultSelector to obtain the final result of Aggregate.

Example

The following code example demonstrates how to use Aggregate to apply an accumulator function and a result selector.

var Enumerable = require("linq-es2015");
 
var fruits = [ "apple", "mango", "orange", "passionfruit", "grape" ];

// Determine whether any string in the array is longer than "banana".
var longestName =
    Enumerable.asEnumerable(fruits)
              .Aggregate("banana", 
                         (longest, next) => next.length > longest.length ? next : longest,
                         // Return the final result as an upper case string.
                         fruit => fruit.toUpperCase());

// This code produces the following output:
// The fruit with the longest name is PASSIONFRUIT. 

Try it out