jokenizer
jokenizer copied to clipboard
:dragon: JavaScript expression tokenizer and evaluator
Jokenizer - JavaScript Expression Parser and Evaluator
jokenizer is just a simple library to parse JavaScript expressions and evaluate them with custom scopes.
Written completely in TypeScript.
Installation
npm i jokenizer
Let's try it out
import { tokenize, evaluate } from 'jokenizer';
const expression = tokenize('{ a: v1, b }');
const scope = { v1: 3, b: 5 };
const value = evaluate(expression, scope);
/*
expression =
{
"type": "O", // ObjectExpression
"members": [{
"type": "A", // AssignExpression
"name": "a",
"right": {
"type": "V", // VariableExpression
"name": "v1"
}
}, {
"type": "V",
"name": "b"
}]
}
value = { "a": 3, "b": 5 } // evaluated value
*/
Supported Expression Types
LiteralExpression
evaluate(tokenize('42')); // 42
evaluate(tokenize('42.4242')); // 42.4242
evaluate(tokenize('"4\'2"')); // "4'2"
evaluate(tokenize('true')); // true
evaluate(tokenize('false')); // false
evaluate(tokenize('null')); // null
VariableExpression
evaluate(tokenize('Name'), { Name: 'Alan' }); // 'Alan'
UnaryExpression
evaluate(tokenize('-Str'), { Str: '5' }); // -5
evaluate(tokenize('+Str'), { Str: '5' }); // 5
evaluate(tokenize('!IsActive'), { IsActive: false }); // true
evaluate(tokenize('~index'), { index: -1 }); // 0
GroupExpression
evaluate(tokenize('(a, b)'), { a: 4, b: 2 }); // [1, 2]
evaluate(tokenize('a, b'), { a: 4, b: 2 }); // [4, 2]
evaluate(tokenize('(a)'), { a: 4 }); // 4 - if expression count is 1, returns its value
ObjectExpression
evaluate(tokenize('{ a: v1, b }'), { v1: 3, b: 5 }); // { a: 3, b: 5 }
ArrayExpression
evaluate(tokenize('[ a, 1 ]'), { a: 0 }); // [0, 1]
BinaryExpression
evaluate(tokenize('v1 <= v2'), { v1: 5, v2: 3 }); // false
evaluate(tokenize('v1 % v2'), { v1: 5, v2: 3 }); // 2
evaluate(tokenize('v1 * v2'), { v1: 5, v2: 3 }); // 15
evaluate(tokenize('v1 && v2'), { v1: true, v2: false }); // false
evaluate(tokenize('1 + 2 * 3')); // 7 - supports operator precedence
MemberExpression
evaluate(tokenize('Company.Name'), { Company: { Name: 'Netflix' } }); // 'Netflix'
IndexerExpression
evaluate(tokenize('Company["Name"]'), { Company: { Name: 'Netflix' } }); // 'Netflix'
evaluate(tokenize('Company[key]'), { Company: { Name: 'Netflix' }, key: 'Name' }); // 'Netflix'
FuncExpression
const f = evaluate(tokenize('(a, b) => a < b'));
f(2, 1); // false
const f = evaluate(tokenize('function(a, b) { return a < b; }'));
f(2, 1) // false
CallExpression
evaluate(tokenize('test(42, a)'), { test: (a, b) => a * b }, { a: 2 }); // 84
TernaryExpression
evaluate(tokenize('check ? 42 : 21'), { check: true }); // 42
License
Jokenizer is under the MIT License.