2020-02-10 03:31:37 +01:00
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<!--
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Copyright JS Foundation and other contributors, http://js.foundation
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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-->
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<script type="text/x-red" data-help-name="function">
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<p>定義對接收到的消息進行處理的JavaScript代碼（函數的主體）。</p>
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<p>輸入消息在名爲<code>msg</code>的JavaScript對象中傳遞。</p>
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<p>通常，<code>msg</code>對象將消息正文保留在<code>msg.payload</code>屬性中。</p>
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<p>該函數一般會返回一個消息對象（或多個消息對象），但也可以爲了停止流程而什麽都不返回。</p>
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<h3>詳細</h3>
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2023-09-05 14:17:55 +02:00
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<p>請參見<a target="_blank" href="https://nodered.org/docs/writing-functions.html">在線文檔</a>來獲得更多有關編寫函數的信息。</p>
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2020-02-10 03:31:37 +01:00
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<h4>傳送消息</h4>
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<p>要將消息傳遞到流程中的下一個節點，請返回消息或調用<code>node.send(messages)</code>。</p>
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<p>它將返回/send:</p>
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<ul>
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<li>單個消息對象 - 傳遞給連接到第一個輸出的節點</li>
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<li>消息對象數組，傳遞給連接到相應輸出的節點</li>
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</ul>
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<p>如果數組元素是數組，則將多個消息發送到相應的輸出。</p>
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<p>無論return方法是單個值還是數組元素，如果返回值爲null，則不會發送任何消息。</p>
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<h4>日志輸出和錯誤處理</h4>
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<p>使用以下功能輸出日志信息和輸出錯誤：</p>
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<ul>
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<li><code>node.log("Log message")</code></li>
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<li><code>node.warn("Warning")</code></li>
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<li><code>node.error("Error")</code></li>
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</ul>
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</p>
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<p>使用catch節點可以進行錯誤處理。 要由catch節點處理，請將<code>msg</code>作爲<code>node.error</code>的第二個參數傳遞：</p>
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<pre>node.error("Error",msg);</pre>
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<h4>訪問節點信息</h4>
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<p>您可以使用以下屬性來在代碼中引用節點ID和名稱：</p>
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<ul>
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<li><code>node.id</code> - 節點的ID</li>
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<li><code>node.name</code> - 節點的名稱</li>
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</ul>
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<h4>使用環境變量</h4>
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<p>環境變量可以通過<code>env.get("MY_ENV_VAR")</code>來進行訪問。</p>
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</script>
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