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Functional Programming Patterns With RamdaJS!

ifElse

Explore how to implement conditional logic in JavaScript with Ramda's ifElse function. Learn to write pure, testable functions that replace traditional if statements and ternary operators. This lesson helps you create cleaner, more maintainable code using functional programming patterns.

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We’re used to seeing if statements like this

Javascript (babel-node)
const hasAccess = true;
if (hasAccess) {
  console.log('Access granted.');
} else {
  console.log('Access denied.');
}

An increasingly popular alternative is the ternary statement.

Javascript (babel-node)
const hasAccess = true;
const message = hasAccess ? 'Access granted.' : 'Access denied.';
console.log(message);

Ramda provides ifElse, letting you handle branching logic with functions.

Javascript (babel-node)
import { ifElse } from 'ramda';
const hasAccess = true;
const logAccess = ifElse(
  () => hasAccess,
  () => console.log('Access granted.'),
  () => console.log('Access denied.')
);
logAccess();

One advantage is that you can package the logic away into a function. Instead of hardcoding the hasAccess variable, make it a parameter.

Javascript (babel-node)
import { ifElse } from 'ramda';
const logAccess = ifElse(
  (hasAccess) => hasAccess,
  () => console.log('Access granted.'),
  () => console.log('Access denied.')
);
logAccess(true);

And instead of the console.log side-effect, purify it by simply returning your desired result.

Javascript (babel-node)
import { ifElse } from 'ramda';
const logAccess = ifElse(
  (hasAccess) => hasAccess,
  () => 'Access granted.',
  () => 'Access denied.'
);
const result = logAccess(true);
console.log({ result });

This makes a point-free style easier to achieve.

Javascript (babel-node)
import { always, equals, ifElse } from 'ramda';
const logAccess = ifElse(
  equals(true),
  always('Access granted.'),
  always('Access denied.')
);
const result = logAccess(true);
console.log({ result });

And the end result’s easier to test!