node-red/nodes/core/core/80-function.html

<script type="text/x-red" data-template-name="function">
    <div class="form-row">
        <label for="node-input-name"><i class="fa fa-tag"></i> <span data-i18n="common.label.name"></span></label>
        <input type="text" id="node-input-name" data-i18n="[placeholder]common.label.name">
    </div>
    <div class="form-row" style="margin-bottom: 0px;">
        <label for="node-input-func"><i class="fa fa-wrench"></i> <span data-i18n="function.label.function"></span></label>
        <input type="hidden" id="node-input-func" autofocus="autofocus">
        <input type="hidden" id="node-input-noerr">
    </div>
    <div class="form-row node-text-editor-row" style="position:relative">
        <div style="position: absolute; right:0; bottom:calc(100% + 3px);"><button id="node-function-expand-js" class="editor-button editor-button-small"><i class="fa fa-expand"></i></button></div>
        <div style="height: 250px; min-height:150px;" class="node-text-editor" id="node-input-func-editor" ></div>
    </div>
    <div class="form-row">
        <label for="node-input-outputs"><i class="fa fa-random"></i> <span data-i18n="function.label.outputs"></span></label>
        <input id="node-input-outputs" style="width: 60px;" value="1">
    </div>
    <div class="form-tips"><span data-i18n="function.tip"></span></div>
</script>

<script type="text/x-red" data-help-name="function">
    <p>A JavaScript function block to run against the messages being received by the node.</p>
    <p>The messages are passed in as a JavaScript object called <code>msg</code>.</p>
    <p>By convention it will have a <code>msg.payload</code> property containing
       the body of the message.</p>
    <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>
    for more information on writing functions.</p>
    <h4>Sending messages</h4>
    <p>The function can either return the messages it wants to pass on to the next nodes
    in the flow, or can call <code>node.send(messages)</code>.</p>
    <p>It can return/send:</p>
    <ul>
      <li>a single message object - passed to nodes connected to the first output</li>
      <li>an array of message objects - passed to nodes connected to the corresponding outputs</li>
    </ul>
    <p>If any element of the array is itself an array of messages, multiple
          messages are sent to the corresponding output.</p>
    <p>If null is returned, either by itself or as an element of the array, no
          message is passed on.</p>
    <h4>Logging and Error Handling</h4>
    <p>To log any information, or report an error, the following functions are available:</p>
      <ul>
          <li><code>node.log("Log message")</code></li>
          <li><code>node.warn("Warning")</code></li>
          <li><code>node.error("Error")</code></li>
      </ul>
    </p>
    <p>The Catch node can also be used to handle errors. To invoke a Catch node,
    pass <code>msg</code> as a second argument to <code>node.error</code>:</p>
    <pre>node.error("Error",msg);</pre>
    <h4>Referring Node Information</h4>
    <p>In the function block, id and name of the node can be referenced using the following properties:</p>
    <ul>
        <li><code>node.id</code> - id of the node</li>
        <li><code>node.name</code> - name of the node</li>
    </ul>
</script>

<script type="text/javascript">
    RED.nodes.registerType('function',{
        color:"#fdd0a2",
        category: 'function',
        defaults: {
            name: {value:""},
            func: {value:"\nreturn msg;"},
            outputs: {value:1},
            noerr: {value:0,required:true,validate:function(v) { return ((!v) || (v === 0)) ? true : false; }}
        },
        inputs:1,
        outputs:1,
        icon: "function.png",
        label: function() {
            return this.name||this._("function.function");
        },
        labelStyle: function() {
            return this.name?"node_label_italic":"";
        },
        oneditprepare: function() {
            var that = this;
            $( "#node-input-outputs" ).spinner({
                min:1,
                change: function(event, ui) {
                    var value = this.value;
                    if (!value.match(/^\d+$/)) { value = 1;  }
                    else if (value < this.min) { value = this.min; }
                    if (value !== this.value) { $(this).spinner("value", value); }
                }
            });

            this.editor = RED.editor.createEditor({
                id: 'node-input-func-editor',
                mode: 'ace/mode/javascript',
                value: $("#node-input-func").val(),
                globals: {
                    msg:true,
                    context:true,
                    RED: true,
                    util: true,
                    flow: true,
                    global: true,
                    console: true,
                    Buffer: true,
                    setTimeout: true,
                    clearTimeout: true,
                    setInterval: true,
                    clearInterval: true
                }
            });

            RED.library.create({
                url:"functions", // where to get the data from
                type:"function", // the type of object the library is for
                editor:this.editor, // the field name the main text body goes to
                mode:"ace/mode/javascript",
                fields:['name','outputs']
            });
            this.editor.focus();

            $("#node-function-expand-js").click(function(e) {
                e.preventDefault();
                var value = that.editor.getValue();
                RED.editor.editJavaScript({
                    value: value,
                    cursor: that.editor.getCursorPosition(),
                    complete: function(v,cursor) {
                        that.editor.setValue(v, -1);
                        that.editor.gotoLine(cursor.row+1,cursor.column,false);
                        setTimeout(function() {
                            that.editor.focus();
                        },300);
                    }
                })
            })
        },
        oneditsave: function() {
            var annot = this.editor.getSession().getAnnotations();
            this.noerr = 0;
            $("#node-input-noerr").val(0);
            for (var k=0; k < annot.length; k++) {
                //console.log(annot[k].type,":",annot[k].text, "on line", annot[k].row);
                if (annot[k].type === "error") {
                    $("#node-input-noerr").val(annot.length);
                    this.noerr = annot.length;
                }
            }
            $("#node-input-func").val(this.editor.getValue());
            this.editor.destroy();
            delete this.editor;
        },
        oneditcancel: function() {
            this.editor.destroy();
            delete this.editor;
        },
        oneditresize: function(size) {
            var rows = $("#dialog-form>div:not(.node-text-editor-row)");
            var height = $("#dialog-form").height();
            for (var i=0; i<rows.size(); i++) {
                height -= $(rows[i]).outerHeight(true);
            }
            var editorRow = $("#dialog-form>div.node-text-editor-row");
            height -= (parseInt(editorRow.css("marginTop"))+parseInt(editorRow.css("marginBottom")));
            $(".node-text-editor").css("height",height+"px");
            this.editor.resize();
        }
    });
</script>