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Datastar Helper Functions

Advanced signal patterns and helper utilities

Logical Operators

Use all_(), any_() helpers and composable operators: & (AND), | (OR), ~ (NOT)

All fields filled:
Form valid (using &):
Has name OR email:
Terms NOT agreed:

Mathematical Operations

Use Math helpers and rounding functions for calculations

Sum:
Maximum:
Square root of A:
Random number: 42

Template Function f_()

Create dynamic template strings with signal interpolation

Basic template:
Email status:
Current time:

Value Fallbacks with expr()

Handle empty or undefined values gracefully using the expr() helper

Name with fallback:
Email with fallback:
Conditional greeting:

Array Operations

Work with arrays using built-in methods and JavaScript helpers

Array contents: [1, 2, 3, 4, 5]
Array length:
Array sum:

Key Takeaways

Use all_() and any_() for readable multi-condition logic
Leverage Math.* functions for calculations and rounding
f_() templates handle complex string interpolation
Pipe operator (|) creates fallbacks using JavaScript's || logic
Array methods (.push, .length) provide clean manipulation
JavaScript expressions integrate seamlessly with Python signals