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简单的 GET 请求

问题

你想向一个网站发起一个简单的 GET 请求并提取有用的信息。

解决方案

使用 HTTP Request 节点发起 HTTP 请求,使用 HTML 节点从获取的 HTML 文档中提取元素。

示例

[{"id":"d88dd470.0ac7b8","type":"inject","z":"18c99b30.cf9d35","name":"发起请求","topic":"","payload":"","payloadType":"date","repeat":"","crontab":"","once":false,"x":130,"y":180,"wires":[["874a3d4e.9b666"]]},{"id":"874a3d4e.9b666","type":"http request","z":"18c99b30.cf9d35","name":"","method":"GET","ret":"txt","url":"https://nodered.org","tls":"","x":294.5,"y":180,"wires":[["90243cc1.87edc"]]},{"id":"7403c68f.21d7c8","type":"debug","z":"18c99b30.cf9d35","name":"","active":true,"console":"false","complete":"false","x":650,"y":180,"wires":[]},{"id":"90243cc1.87edc","type":"html","z":"18c99b30.cf9d35","name":"","property":"","tag":".node-red-latest-version","ret":"text","as":"single","x":471.5,"y":180,"wires":[["7403c68f.21d7c8"]]}]

讨论

要在网页中查找内容,Chrome 浏览器的“检查元素”工具可能是一个有用的工具。使用浏览器,右键点击页面元素以查看应用于该元素的标签、ID 和类,如下所示。

在这个例子中,我们从 https://nodered.org 中检索 Node-RED 的最新版本。使用检查器,我们可以看到版本信息位于一个 <span> 标签内,类名为 node-red-latest-version

HTML 节点可以配置使用 CSS 选择器 .node-red-latest-version,以返回每个匹配元素的消息。