backstopTools.js

var BODY_SELECTOR = 'body';
var DOCUMENT_SELECTOR = 'document';
var VIEWPORT_SELECTOR = 'viewport';
var INJECT_CSS = 'html {-webkit-font-smoothing: antialiased;}';

function injectStyle (cssSting) {
  var styleTag = document.createElement('style');
  styleTag.innerHTML = cssSting;
  document.body.appendChild(styleTag);
}
injectStyle(INJECT_CSS);

/**
 * Take an array of selector names and return and array of *all* matching selectors.
 * For each selector name, If more than 1 selector is matched, proceeding matches are
 * tagged with an additional `__n` class.
 *
 * @param  {[string]} collapsed list of selectors
 * @return {[string]} [array of expanded selectors]
 */
window.expandSelectors = function (selectors) {
  if (!Array.isArray(selectors)) {
    selectors = selectors.split(',');
  }
  return selectors.reduce(function (acc, selector) {
    if (selector === BODY_SELECTOR || selector === VIEWPORT_SELECTOR) {
      return acc.concat([selector]);
    }
    if (selector === DOCUMENT_SELECTOR) {
      return acc.concat([DOCUMENT_SELECTOR]);
    }
    var qResult = document.querySelectorAll(selector);

    // pass-through any selectors that don't match any DOM elements
    if (!qResult.length) {
      return acc.concat(selector);
    }

    var expandedSelector = [].slice.call(qResult)
      .map(function (element, expandedIndex) {
        if (element.classList.contains('__86d')) {
          return '';
        }
        if (!expandedIndex) {
          // only first element is used for screenshots -- even if multiple instances exist.
          // therefore index 0 does not need extended qualification.
          return selector;
        }
        // create index partial
        var indexPartial = '__n' + expandedIndex;
        // update all matching selectors with additional indexPartial class
        element.classList.add(indexPartial);
        // return array of fully-qualified classnames
        return selector + '.' + indexPartial;
      });
    // concat arrays of fully-qualified classnames
    return acc.concat(expandedSelector);
  }, []).filter(function (selector) {
    return selector !== '';
  });
};

window.isVisible = function (selector) {
  if (selector === BODY_SELECTOR || selector === DOCUMENT_SELECTOR || selector === VIEWPORT_SELECTOR) {
    return true;
  } else if (window.exists(selector)) {
    const element = document.querySelector(selector);
    const style = window.getComputedStyle(element);
    return (style.display !== 'none' && style.visibility !== 'hidden' && style.opacity !== '0');
  }
  return false;
};

window.exists = function (selector) {
  if (selector === BODY_SELECTOR || selector === DOCUMENT_SELECTOR || selector === VIEWPORT_SELECTOR) {
    return 1;
  }
  return document.querySelectorAll(selector).length;
};

var _consoleLogger = '';
window._hasLogged = function (str) {
  return new RegExp(str).test(_consoleLogger);
};
function startConsoleLogger () {
  var log = console.log.bind(console);
  console.log = function () {
    _consoleLogger += Array.from(arguments).join('\n');
    log.apply(this, arguments);
  };
}
startConsoleLogger();

console.info('backstopTools are running');