sock_decify.js

// Our original Code
var variant = {{ current_variant | json }};
if (variant){
  var fields = JSON.parse('{{ product.metafields.decify | json }}');
  if(typeof fields[variant.id] !== 'undefined') {
     console.log("Variant found, using custom URL.");
     document.getElementById("customize-btn").href = fields[variant.id];
  }
}

//Script that was added
document.getElementById('customize-btn').addEventListener('click', function(){
  window.event.preventDefault();

  var fields = JSON.parse('{{ product.metafields.decify | json }}');
  var current_variant = document.getElementsByName('id')[0].value;
  var decify_link = fields[current_variant];

  console.log('current', current_variant);
  document.location.href = decify_link;
});