'reduce' function is used to combine elements of array using given combiner function.
Syntax
arr.reduce(callback[,
initialValue])
callback
function takes four arguments.
Argument
|
Description
|
previousValue
|
The
value previously returned in the last invocation of the callback, or
initialValue, if supplied.
|
currentValue
|
The
current element being processed in the array.
|
currentIndex
|
The
index of the current element being processed in the array. Starts at index 0,
if an initialValue is provided, and at index 1 otherwise.
|
array
|
The
array reduce was called upon.
|
initialValue
It is
optional, Value to use as the first argument to the first call of the callback.
function
add(x, y){
return x+y;
}
var
sumOfEle = arr1.reduce(add, 0);
Above
statements are used to calculate sum of elements of the array.
function
mul(x, y){
return x*y;
}
var
mulOfEle = arr1.reduce(mul, 1);
Above
statements are used to compute multiplication of elements in array.
function
max(x, y){
return ((x>y)?x:y);
}
var maximum
= arr1.reduce(max);
Above
statements are used to compute maximum value in the array.
reduce.html
<!DOCTYPE html> <html> <head> <title>Array reduce example</title> </head> <body> <script type="text/javascript"> var arr1 = [12, 43, 2, 3, 98, 6]; function add(x, y) { return x + y; } function mul(x, y) { return x * y; } function max(x, y) { return ((x > y) ? x : y); } var sumOfEle = arr1.reduce(add, 0); var mulOfEle = arr1.reduce(mul, 1); var maximum = arr1.reduce(max); document.write("Sum of elements in array is " + sumOfEle + "<br />"); document.write("Multiplication of elements in array is " + mulOfEle + "<br />"); document.write("Maximum number in array is " + maximum + "<br />"); </script> </body> </html>
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