Expression

This node executes custom JavaScript expressions.

The Expression node allows you to run snippets of JavaScript code directly within the graph.

The Expression node is a powerful tool for executing custom JavaScript logic. It allows you to write a single-line or multi-line expression that returns a value. It supports dynamic inputs, meaning you can add variables to your expression (e.g., a + b) and the node will automatically create input ports for them.

Inputs

General

Data	Description
Expression	The JavaScript code to execute. This is a special input that opens a code editor. Variables used in the code (e.g., x, y, myVar) become dynamic inputs on the node.

Dynamic Inputs

Data	Description
*	Any variable name used in your expression will appear as an input port. Connect data to these ports to use them in your code.

Actions

Signal	Description
Run	Triggers the execution of the expression. If not connected, the expression runs automatically whenever any input changes.

Outputs

Result

Data	Description
Result	The return value of the expression.
Is True	Boolean: true if the result is truthy.
Is False	Boolean: true if the result is falsy.

Events

Signal	Description
On True	Triggered if the result is truthy.
On False	Triggered if the result is falsy.

Usage

Writing Expressions

The code you write is wrapped in a function. You should return a value.

• Simple Math: a * b + c (Creates inputs a, b, c)
• String Logic: firstName + " " + lastName (Creates inputs firstName, lastName)
• Complex Logic:

  if (score > 100) {
    return "Winner";
  } else {
    return "Try Again";
  }

Available Globals

The following Math functions are available directly without the Math. prefix:

• min, max, round, floor, ceil, abs, random, sqrt, sin, cos, tan, pi

Auto-Run vs. Manual Run

• Auto-Run: If the Run input is NOT connected, the expression evaluates every time any of its data inputs change.
• Manual Run: If you connect a signal to Run, the expression only evaluates when that signal is triggered. This is useful for expensive calculations or when you want to synchronize with a button press.

Detailed Behavior

1. Parsing: The node parses your code to find variable names and creates inputs for them.
2. Scope: Inputs are injected into the function scope.
3. Execution: The code is compiled into a function and executed safely.
4. Error Handling: Runtime errors are logged to the console and may trigger editor warnings. The result defaults to 0 on error.

Troubleshooting

• Inputs Not Showing: Ensure your variable names are valid JavaScript identifiers (e.g., no spaces, don't start with numbers).
• Result is 0: Check the console for syntax errors or runtime exceptions.
• Infinite Loops: Avoid while(true) loops; the execution environment attempts to be safe but can still freeze if you write blocking code.