'use strict'; var appContainer = document.getElementById('app-container'); var zipcodeInput = document.getElementById('zipcode-input'); var addLocationBtn = document.getElementById('add-location'); var btnClickStream = Rx.Observable.fromEvent(zipcodeInput, 'input').map(function (e) { return e.target.value; }).filter(function (zip) { return zip.length === 5; }).forEach(function (val) { return console.log('zipInputStream val', val); });