kibana/docs/development/plugins/expressions/public/kibana-plugin-plugins-expressions-public.isexpressionastbuilder.md

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isExpressionAstBuilder() function

Type guard that checks whether a given value is an ExpressionAstExpressionBuilder. This is useful when working with subexpressions, where you might be retrieving a function argument, and need to know whether it is an expression builder instance which you can perform operations on.

Signature:

export declare function isExpressionAstBuilder(val: any): val is ExpressionAstExpressionBuilder;

Parameters

Parameter	Type	Description
val	any

Returns:

val is ExpressionAstExpressionBuilder

Example

const arg = myFunction.getArgument('foo'); if (isExpressionAstBuilder(foo)) { foo.toAst(); }