pure smallEnought version

small-enought.js

/**
 * pure smallEnought version
 * @param {array} a 
 * @param {number} limit 
 */
const smallEnought = ([head, ...tail], limit) => (!head && !tail.length) || ((head > limit) ? false : smallEnought(tail, limit))

Extended version

const smallEnought = (a, limit) => {
  //destruct array
  const [head, ...tail] = a
  //stop positively when there nothing more to look for
  if(!head && !tail.length){
    return true
  }
  //if the first item of array is larger than limit return false otherwise call itself with the remaining elements
  return ((head > limit) ? false : smallEnought(tail, limit))
}

Tests

const assert = require('assert')
assert.equal(smallEnought([5, 4, 3, 2, 1], 4), false)
assert.equal(smallEnought([2, 4, 3, 2, 1], 4), true)
assert.equal(smallEnought([4, 4, 3, 2, 1], 4), true)
assert.equal(smallEnought([2, 4, 3, 2, 5], 4), false)
assert.equal(smallEnought([2, 7, 3, 2, 5], 4), false)