In Java 8 using streams when I chain methods one after the another the execution of operations are performed in pipelined manner.
Example:
List<Integer> nums = Arrays.asList(1,2,3,4,5,6);
nums.stream().map(x->{
x = x * x;
System.out.println("map1="+x);
return x;
}).map(x->{
x = x * 3;
System.out.println("map2="+x);
return x;
}).forEach(x-> System.out.println("forEach="+x));
Output:-
map1=1
map2=3
forEach=3
map1=4
map2=12
forEach=12
map1=9
map2=27
forEach=27
map1=16
map2=48
forEach=48
map1=25
map2=75
forEach=75
map1=36
map2=108
forEach=108
But when I tried similarly in javascript.The result is different.As in javascript first operation gets completed and then second operation is performed.Example:-
var nums = [1,2,3,4,5,6 ];
nums.map(x => {
x = (x * x);
console.log('map1='+x);
return x;})
.map(x => {
x = x * 3;
console.log('map2='+x);
return x;})
.forEach(x=> console.log('forEach='+x));
Output:-
map1=1
map1=4
map1=9
map1=16
map1=25
map1=36
map2=3
map2=12
map2=27
map2=48
map2=75
map2=108
forEach=3
forEach=12
forEach=27
forEach=48
forEach=75
forEach=108
Is there any way in JavaScript to make it performs operations in a pipeline manner, and I get output as in the Java program?
Maybe later (or never) you can use the actual experimental pipeline operator |>
, which has the following syntax:
expression |> function
Your wanted result could be achieved by taking the functions as separate functions and iterate the stream array for each pipe.
This works only in FF. From version 58: this feature is behind the --enable-pipeline-operator
compile flag.
const
a = x => { x = x * x; console.log("map1=" + x); return x; },
b = x => { x = x * 3; console.log("map2=" + x); return x; },
c = x => console.log("forEach=" + x)
var nums = [1, 2, 3, 4, 5, 6];
nums.forEach(v => v |> a |> b |> c);
The same with a pipe as function (function composition enabling piping) with a closure over the wanted functions.
const
pipe = (...functions) => input => functions.reduce((acc, fn) => fn(acc), input),
a = x => { x = x * x; console.log("map1=" + x); return x; },
b = x => { x = x * 3; console.log("map2=" + x); return x; },
c = x => console.log("forEach=" + x)
var nums = [1, 2, 3, 4, 5, 6],
pipeline = pipe(a, b, c);
nums.forEach(pipeline);