@bufbuild/cel

@bufbuild/cel

This package provides a CEL evaluator for ECMAScript.

Example

Let's evaluate a CEL expression that has the variable name and uses the strings extension functions:

import { run } from "@bufbuild/cel";
import { STRINGS_EXT_FUNCS } from "@bufbuild/cel/ext/strings";

run(
  `name.indexOf('taco') == 0`,
  {name: "tacocat"},
  {funcs: STRINGS_EXT_FUNCS },
); // true

That's it!

For an example of creating resusable evaluator and more, refer to the example.ts.

Types

The table below maps JS types to CEL types.

• Input column is any value that can be passed to the evaluator as input. (CelInput)
• CEL Type column is the CEL type it will represent at runtime. (CelType)
• Output column is the type of values that are returned by the evaluator, either as returned from eval or as arguments to function implementations. (CelValue)

Input (JS Type)	CEL Type (runtime)	Output (JS Type)
number, {Float,Double}Value	double	number
bigint, all signed int wrappers	int	bigint
CelUint, all unsigned int wrappers	uint	CelUint
string, StringValue	string	string
Uint8Array, BytesValue	bytes	Uint8Array
Map, ReflectMap	map	CelMap
any[], ReflectList	list	CelList
boolean, BoolValue	bool	boolean
null	null_type	null
CelType	type	CelType
Timestamp, ReflectMessage	timestamp	ReflectMessage
Duration, ReflectMessage	duration	ReflectMessage
Message, ReflectMessage, Any	<typeName>	ReflectMessage
google.protobuf.Value and friends	double/bool/string/list/map/null	number/boolean/string/CelList/CelMap