JavaScript expression parsing and evaluation.
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JavaScript expression parsing and evaluation.
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Install:
``
npm install --save @casbin/expression-eval
Import:
`js`
// ES6
import { parse, eval } from '@casbin/expression-eval';
// CommonJS
const { parse, eval } = require('@casbin/expression-eval');
// UMD / standalone script
const { parse, eval } = window['@casbin/expression-eval'];
`javascript`
import { parse } from '@casbin/expression-eval';
const ast = parse('1 + foo');
The result of the parse is an AST (abstract syntax tree), like:
`json`
{
"type": "BinaryExpression",
"operator": "+",
"left": {
"type": "Literal",
"value": 1,
"raw": "1"
},
"right": {
"type": "Identifier",
"name": "foo"
}
}
`javascript`
import { parse, eval } from '@casbin/expression-eval';
const ast = parse('a + b / c'); // abstract syntax tree (AST)
const value = eval(ast, {a: 2, b: 2, c: 5}); // 2.4
Alternatively, use evalAsync for asynchronous evaluation.
`javascript`
import { compile } from '@casbin/expression-eval';
const fn = compile('foo.bar + 10');
fn({foo: {bar: 'baz'}}); // 'baz10'
Alternatively, use compileAsync for asynchronous compilation.
Although this package does avoid the use of eval()`, it _cannot guarantee that user-provided expressions, or user-provided inputs to evaluation, will not modify the state or behavior of your application_. This library does not attempt to provide a secure sandbox for evaluation. Evaluation of arbitrary user inputs (expressions or values) may lead to unsafe behavior. If your project requires a secure sandbox, consider alternatives such as vm2.
Apache 2.0 License.