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.
Syntax
typedarray.reduceRight(callback[, initialValue])
Parameters
callback
- Function to execute on each value in the typed array, taking four arguments:
previousValue
- 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
reduce
was called upon.
initialValue
- Optional. Object to use as the first argument to the first call of the
callback
.
Return value
The value that results from the reduction.
Description
The reduceRight
method executes the callback 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 callback 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(function(previousValue, currentValue, index, typedarray) { // ... });
The first time the function is called, the previousValue
and currentValue
can be one of two values. If an initialValue
was provided in the call to reduceRight
, then previousValue
will be equal to initialValue
and currentValue
will be equal to the last value in the typed array. If no initialValue
was provided, then previousValue
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 callback
.
Examples
Sum up all values within an array
var total = new Uint8Array([0, 1, 2, 3]).reduceRight(function(a, b) { return a + b; }); // total == 6
Specifications
Specification | Status | Comment |
---|---|---|
ECMAScript 2015 (6th Edition, ECMA-262) The definition of '%TypedArray%.prototype.reduceRight' in that specification. |
Standard | Initial definition. |
ECMAScript 2017 Draft (ECMA-262) The definition of '%TypedArray%.prototype.reduceRight' in that specification. |
Draft |
Browser compatibility
Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari |
---|---|---|---|---|---|
Basic support | ? | 37 (37) | ? | ? | ? |
Feature | Android | Chrome for Android | Firefox Mobile (Gecko) | IE Mobile | Opera Mobile | Safari Mobile |
---|---|---|---|---|---|---|
Basic support | ? | ? | 37.0 (37) | ? | ? | ? |