A configurable eval function, which uses jsep to parse expressions. The generated result is evaluated w.r.t. a supplied object context.

Usage no npm install needed!

<script type="module">
  import sensativeJsepEval from 'https://cdn.skypack.dev/@sensative/jsep-eval';


jsep-eval: evaluate javascript expressions

jsep-eval evaluates javascript expressions, and uses jsep to parse the expressions. A context can/should be supplied against which identifers are matched.



First, run npm install jsep-eval. Then, in your source file:

const jsepEval = require("jsep-eval");
const evaluate = jsepEval.evaluate;
const two = evaluate('1 + 1');
const three = evaluate('two + 1', {two: 2});

Configure evaluation restrictively

jsep-eval exposes the objects the allowed expression types

const types = jsepEval.types;

So it is possible to dis-allow a given expression type by removing it from this array:

const types = jsepEval.types;
evaluate('2 + 2'); // returns 4
delete types.BINARY;
evaluate('2 + 2'); // throws error

It is also possible to restrict evaluation by operator (both binary and unary):

const binaryOps = jsepEval.operators.binary;
const unaryOps = jsepEval.operators.unary;

evaluate('2 === 2'); // returns true
delete binaryOps['==='];
evaluate('2 === 2'); // throws error

evaluate('!false'); // returns true
unaryOps['!'] = () => 'bob';
evaluate('!false'); // returns 'bob'


jsep-eval is under the MIT license. See LICENSE file.