JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://cdn.rawgit.com/ansman/validate.js/0.11.1/validate.js"></script>

JavaScript

var a = ['', ' ', '  ', '012345'];
  
a.forEach(function (v) {
 	console.log('value |%s|', v);
  
	console.log('allowEmpty true' , validate.single(v, {
  	presence: {
    	allowEmpty: true,
      message: 'Invalid from presence'
    },
    format: {
    	pattern: "^.{1,5}$",
      message: 'Invalid from format',
    },
  }));
  
	console.log('allowEmpty false', validate.single(v, {
  	presence: {
    	allowEmpty: false,
      message: 'Invalid from presence',
    },
    format: {
    	pattern: "^.{1,5}$",
      message: 'Invalid from format',
    },
  }));
  
  console.log('')
 });