ws.js

var ws = new WebSocket('...');

var timeout = setTimeout(function() {
  console.log('fuuuuuuuu', ws.readyState);
  ws.close();
}, monSuperTimeout);

ws.onopen = function(event) {
  clearTimeout(timeout);
  ...
};

ws.onclose = function(event) {
  clearTimeout(timeout);
  ...
};