TypedArray.prototype.reduceRight()
The reduceRight()
method applies a function against an
accumulator and each value of the typed array (from right-to-left) has to reduce it to a
single value. This method has the same algorithm as
Array.prototype.reduceRight()
. TypedArray is one of the
typed array types here.
Try it
Syntax
// Arrow function
reduceRight((accumulator, currentValue) => { /* ... */ } )
reduceRight((accumulator, currentValue, index) => { /* ... */ } )
reduceRight((accumulator, currentValue, index, array) => { /* ... */ } )
reduceRight((accumulator, currentValue, index, array) => { /* ... */ }, initialValue)
// Callback function
reduceRight(callbackFn)
reduceRight(callbackFn, initialValue)
// Inline callback function
reduceRight(function(accumulator, currentValue) { /* ... */ })
reduceRight(function(accumulator, currentValue, index) { /* ... */ })
reduceRight(function(accumulator, currentValue, index, array){ /* ... */ })
reduceRight(function(accumulator, currentValue, index, array) { /* ... */ }, initialValue)
Parameters
callbackFn
-
Function to execute on each value in the typed array.
The function is called with the following arguments:
accumulator
-
The value previously returned in the last invocation of the callback, or
initialValue
, if supplied (see below). currentValue
-
The current element being processed in the typed array.
index
-
The index of the current element being processed in the typed array.
array
-
The typed array
reduceRight()
was called upon.
initialValue
-
Optional. Object to use as the first argument to the first call of the
callbackFn
.
Return value
The value that results from the reduction.
Description
The reduceRight
method executes the callbackFn
function once for each element present in the typed array, excluding holes in the typed
array, receiving four arguments: the initial value (or value from the previous
callbackFn
call), the value of the current element, the current
index, and the typed array over which iteration is occurring.
The call to the reduceRight
callback would look something like this:
typedarray.reduceRight((accumulator, currentValue, index, typedarray) => {
// ...
});
The first time the function is called, the accumulator
and
currentValue
can be one of two values. If an
initialValue
was provided in the call to
reduceRight
, then accumulator
will be equal to
initialValue
and currentValue
will be
equal to the last value in the typed array. If no initialValue
was provided, then accumulator
will be equal to the last value
in the typed array and currentValue
will be equal to the
second-to-last value.
If the typed array is empty and no initialValue
was provided,
TypeError
would be thrown. If the typed array has only one element
(regardless of position) and no initialValue
was provided, or if
initialValue
is provided but the typed array is empty, the solo
value would be returned without calling callbackFn
.
Examples
Sum up all values within an array
const total = new Uint8Array([0, 1, 2, 3]).reduceRight((a, b) => a + b);
// total === 6
Specifications
Specification |
---|
ECMAScript Language Specification # sec-%typedarray%.prototype.reduceright |
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