CODEWITHSUNDEEP
javascriptramda.js
bytevic
bytevic

Reputation: 53

How to rewrite this ramda.js code in vanilla JS

I am removing ramda from some code I've inherited as part of an effort to reduce the JavaScript size. But I'm stuck with the below because this line really baffles me as it apparently doesn't operate on any object.

var iterate = R.addIndex(R.forEach);

The relevant code looks like this:

var lis = $(el).find("ul.navbar-nav:not(.navbar-right) > li:not(.nav-more)");

var iterate = R.addIndex(R.forEach);

iterate(function(li) {
    // Other code

}, lis);

How can I write it in vanilla JS?

Upvotes: 4

Views: 276

Answers (2)

Ori Drori
Ori Drori

Reputation: 191936

Convert the object to a standard array using Array.from() and then you JS Array.forEach():

const iterate = (fn, o) => Array.from(o).forEach(fn)

iterate(function(li) {
  // Other code   
}, lis);

Upvotes: 2

VLAZ
VLAZ

Reputation: 28958

When R.addIndex() is applied to R.forEach() it creates a function that simply iterates over the items and for each assigns an index starting from zero: 

var lis = ["a", "b", "c"];

var iterate = R.addIndex(R.forEach);

iterate(function(li, index) {
  console.log(li, index)
}, lis);
<script src="//cdn.jsdelivr.net/npm/[email protected]/dist/ramda.min.js"></script>

This is very easy to replace with vanilla JavaScript using Array.from with Array.forEach():

var lis = ["a", "b", "c"];

var iterate = (fn, list) =>
  Array.from(list)
    .forEach(fn);

iterate(function(li, index) {
  console.log(li, index);
}, lis);

In case Array.from() is not available and an ES5 solution is needed, then Array.prototype.slice() can be used to convert to array:

var lis = ["a", "b", "c"];

var iterate = function(fn, list) {
  Array.prototype.slice.call(list)
    .forEach(fn);
}

iterate(function(li, index) {
  console.log(li, index);
}, lis);

Finally, it is possible to convert to a simple for loop that works with any array-like

var lis = ["a", "b", "c"];

var iterate = function(fn, list) {
  for (var i = 0; i < list.length; i++)
    fn(list[i], i);
}

iterate(function(li, index) {
  console.log(li, index);
}, lis);

Upvotes: 2

Related Questions