BackstopJS 是自动 CSS 回归测试工具，它通过比较不同视窗大小的 DOM 截图来回应你所测试的 Web 界面。可以识别出两个不同视角上的网页差异。
{ "viewports": [ { "name": "phone", "width": 320, "height": 480 }, { "name": "tablet_v", "width": 568, "height": 1024 }, { "name": "tablet_h", "width": 1024, "height": 768 } ], "scenarios": [ { "label": "http://getbootstrap.com", "url": "http://getbootstrap.com", "hideSelectors": [], "removeSelectors": [ "#carbonads-container" ], "selectors": [ "header", "main", "body .bs-docs-featurette:nth-of-type(1)", "body .bs-docs-featurette:nth-of-type(2)", "footer", "body" ], "readyEvent": null, "delay": 500 } ]}
