How can I perform operations in JavaScript just like we do pipeline of operations in Java streams?

Question

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

Example:

List

        

Answer 1

The equivalent to Java's streams are JavaScript's iterators. Iterator objects unfortunately don't have a map method (yet), but you can easily write one yourself (and even install it on the prototype if you want method syntax).

function* map(iterable, f) {
    for (var x of iterable)
        yield f(x);
}

var nums = [1,2,3,4,5,6];
function square(x) {
  x = (x * x);
  console.log('map1='+x);
  return x;
}
function triple(x) {
  x = x * 3;
  console.log('map2='+x);
  return x;
}
for (const x of map(map(nums.values(), square), triple)) {
  console.log('forEach='+x);
}

Also notice that in functional programming, order doesn't matter for pure operations - you shouldn't need to rely on the execution order if you are using map.