node-red/packages/node_modules/@node-red/nodes/core/core/80-function.html

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    <p>A JavaScript function block to run against the messages being received by the node.</p>
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    <p>The function is expected to return a message object (or multiple message objects), but can choose
       to return nothing in order to halt a flow.</p>
    <h3>Details</h3>
    <p>See the <a target="_blank" href="http://nodered.org/docs/writing-functions.html">online documentation</a>
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    <h4>Sending messages</h4>
    <p>The function can either return the messages it wants to pass on to the next nodes
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    <p>The Catch node can also be used to handle errors. To invoke a Catch node,
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    <h4>Accessing Node Information</h4>
    <p>In the function block, id and name of the node can be referenced using the following properties:</p>
    <ul>
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        <li><code>node.name</code> - name of the node</li>
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    <h4>Using environment variables</h4>
    <p>Environment variables can be accessed using <code>env.get("MY_ENV_VAR")</code>.</p>
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