就像我们在Java流中执行流水线一样，如何在JavaScript中执行操作? [英] How can I perform operations in JavaScript just like we do pipeline of operations in Java streams?

问题描述

在使用流的Java 8中，当我一个接一个地链接方法时，以流水线方式执行操作.

In Java 8 using streams when I chain methods one after the another the execution of operations are performed in pipelined manner.

示例:

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));

输出:-

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

但是当我在javascript中进行类似尝试时，结果却不同.与javascript中一样，第一个操作完成了，然后执行了第二个操作.示例:-

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));

输出:-

 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

JavaScript中是否有任何方法可以使其以管道方式执行操作，并且获得Java程序中的输出?

Is there any way in JavaScript to make it performs operations in a pipeline manner, and I get output as in the Java program?

此问题仅询问如何在JavaScript中收集内容，而不询问内部工作方式如何变化相同类型的方法.

推荐答案

也许稍后(或永远不会)，您可以使用实际的实验

Maybe later (or never) you can use the actual experimental pipeline operator |>, which has the following syntax:

expression |> function

通过将这些函数作为单独的函数并为每个管道迭代流数组，可以实现所需的结果.

Your wanted result could be achieved by taking the functions as separate functions and iterate the stream array for each pipe.

这仅在FF中有效.从58版开始:此功能位于-enable-pipeline-operator 编译标志的后面.

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);

与带有管道的函数相同(

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);

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