what is immutable
// by negative example here is how to make a javascript immutable 'use strict'; const a = Object.freeze([4, 5, 6]); // Instead of: a.push(7, 8, 9); const b = a.concat(7, 8, 9); // Instead of: a.pop(); const c = a.slice(0, -1); // Instead of: a.unshift(1, 2, 3); const d = [1, 2, 3].concat(a); // Instead of: a.shift(); const e = a.slice(1); // Instead of: a.sort(myCompareFunction); const f = R.sort(myCompareFunction, a); // R = Ramda // Instead of: a.reverse(); const g = R.reverse(a); // R = Ramda
