Super lightweight, fast, and optimized evaluate-able and compilable expressions in JSON written in TypeScript
npm install -D expjson
or
yarn add -D expjson
compileExpression and running it later is much faster if compiled expression is evaluated multiple times on many execution contexts.
evaluateExpression is faster if the expression is evaluated only once.
functionalities are exactly same for both.
import {
compileExpression,
evaluateExpression,
// operators
Add,
And,
Divide,
Equal,
GreaterThan,
GreaterThanOrEqual,
IfThenElse,
In,
LessThan,
LessThanOrEqual,
Modulo,
Multiply,
Not,
NotEqual,
NotIn,
Or,
Subtract,
Var,
} from 'expjson';
// evaluateExpression: evaluate without compile
expect(
evaluateExpression(
[
IfThenElse, // same as '?:'
[In, 'admin', [Var, 'roles']], // test if "admin" is in "roles" context variable
[Not, [Var, 'postDeleted']], // true if context variable "postDeleted" is false
[Var, 'unauthorized'], // context variable "unauthorized"
],
{
postDeleted: false,
roles: ['user', 'admin'],
unauthorized: 'Unauthorized Error',
}
)
).toBe(true);
expect(
evaluateExpression(
[
'?:', // same as IfThenElse
['In', 'admin', [Var, 'roles']], // test if "admin" is in "roles" context variable
['!', [Var, 'postDeleted']], // true if context variable "postDeleted" is false
[Var, 'unauthorized'], // context variable "unauthorized"
],
{
postDeleted: true,
roles: ['user', 'admin'],
unauthorized: 'Unauthorized Error',
}
)
).toBe(false);
expect(
evaluateExpression(
[
IfThenElse, // same as '?:'
[In, 'admin', [Var, 'roles']], // test if "admin" is in "roles" context variable
[Not, [Var, 'postDeleted']], // true if context variable "postDeleted" is false
[Var, 'unauthorized'], // context variable "unauthorized"
],
{
postDeleted: false,
roles: ['user', 'guest'],
unauthorized: 'Unauthorized Error',
}
)
).toBe('Unauthorized Error');
// compileExpression: compile then evaluate
const compiled1 = compileExpression([
IfThenElse, // same as '?:'
[In, 'admin', [Var, 'roles']], // test if "admin" is in "roles" context variable
[Not, [Var, 'postDeleted']], // true if context variable "postDeleted" is false
[Var, 'unauthorized'], // context variable "unauthorized"
]);
expect(
compiled1({
postDeleted: false,
roles: ['user', 'admin'],
unauthorized: 'Unauthorized Error',
})
).toBe(true);
const compiled2 = compileExpression([
'?:', // same as IfThenElse
['In', 'admin', [Var, 'roles']], // test if "admin" is in "roles" context variable
['!', [Var, 'postDeleted']], // true if context variable "postDeleted" is false
[Var, 'unauthorized'], // context variable "unauthorized"
]);
expect(
compiled2({
postDeleted: true,
roles: ['user', 'admin'],
unauthorized: 'Unauthorized Error',
})
).toBe(false);
const compiled3 = compileExpression([
IfThenElse, // same as '?:'
[In, 'admin', [Var, 'roles']], // test if "admin" is in "roles" context variable
[Not, [Var, 'postDeleted']], // true if context variable "postDeleted" is false
[Var, 'unauthorized'], // context variable "unauthorized"
]);
expect(
compiled3({
postDeleted: false,
roles: ['user', 'guest'],
unauthorized: 'Unauthorized Error',
})
).toBe('Unauthorized Error');