js.eval

 This article describes a feature or macro function that is experimental and may be subject to change.

js.eval() Function

 Note: This function can only be used in a Trusted Macro

• Introduced in version 1.10.0

Evaluates a string as a javascript expression within the embedded GraalVM interpreter (this is NOT the same JavaScript environment as that provided by the HTML5 functions). Supports ECMA 2021 standard. For security, access to native types and external resources are limited. Similarly, all arrays passed in to the javascript environment are shallow copied, so changes to the array do not directly change MapTool's state. Starting in 1.10.0, the context in which the javascript fragment executes is discarded when

js.eval

returns. For setting up persistent structures, see js.evalNS() or js.evalURI()

Usage

js.eval(expression, arg1, arg2...)

Parameters

• expression - A valid javascript fragment. It is wrapped inside an anonymous function.
• arg1, arg2... - Any. Will be converted to the equivalent javascript type as needed. Arguments are accessible via the args variable.
• return - Any primitive type; Complex types are converted to (JSON) strings.

Example

Using js.eval on an expression.

[r: js.eval("let a = [1,2,3]; return a[1] + args[0]", 5)]

Output:

7

See Also

JS: MapTool

JS: MTScript
js.evalNS()

js.evalURI()