applyVariants.js

/*
    Running Variants locally without the editor
    Authored by Richard Cowin
    
    Disable content security policy with Resource Override
    This will allow for local host
    window.applyVariants(‘http://localhost:8000/t-and-c/’, [‘v1’]);
*/

window.applyVariants = function applyVariants(folder, variants, poll) {
  poll = poll || {duration: 30000, interval:50};
  function getRule() { return window.evolv && window.evolv.renderRule }
  function loadVariants() {
    console.info('loading context')
    loadScript(`${folder}context.js`)
    loadStyles(`${folder}context.css`)
    variants.forEach(v => {
      console.info('loading variant', v)
      loadScript(`${folder}${v}.js`)
      loadStyles(`${folder}${v}.css`)
    })
  }
  waitFor(getRule, loadVariants, poll)
}
function loadScript(path) {
  var scriptNode = document.createElement('script');
  scriptNode.setAttribute('src', path);
  document.head.appendChild(scriptNode);
}
function loadStyles(path){
  // link rel="stylesheet" href="styles.css"
  var styleNode = document.createElement('link');
  styleNode.setAttribute('rel', 'stylesheet');
  styleNode.setAttribute('href', path);
  document.head.appendChild(styleNode);
}
function listenToEvents(config) {
  var poll = config.poll || {duration: 2000, interval:50 };
  function getRule() { return window.evolv && window.evolv.renderRule }
  waitFor(getRule, inject, poll);
}
function waitFor(check, invoke, poll) {
  if (check()) {
      invoke();
      return;
  }
  var polling = setInterval(function() {
    try {
      if (check()) {
        invoke();
        clearInterval(polling);
        polling = null;
      }
    } catch(e) { console.info('listener not processed') }
  }, poll.interval)
  setTimeout(function() { 
      if (!polling) return
      
      clearInterval(polling)     
      console.info('listener timeout')
  }, poll.duration)
}