Safe JS CodeScriptExecutor

code_script_executor.js

/**
 * @file code_script_executor.js
 * @author tynrare
 * @version 1
 * @module Core/Lib/CodeScriptExecutor
 */

/**
 * Allows to execute js script from strings with scope bindings
 */
class CodeScriptExecutor {
	/**
	 * Binds object into string function scope
	 *
	 * #chainable
	 *
	 * @param {object} object object to bind into scope
	 * @param {string} name name this object avaible in function scope
	 * @example
	 *
	 * const a = { foo: 1 }
	 * const b = { bar: 2 }
	 * executor.bind(a, 'a').bind(b, 'b')
	 * const result = executor.execute('a.foo+b.bar'); //3
	 *
	 * @returns {CodeScriptExecutor} this
	 */
	bind(object, name) {
		this.bindedObjects[name] = object;

		this.bindedObjectsStringCache += `var ${name} = args[${this.bindedObjectsCountCache++}];`;

		return this;
	}

	/**
	 * Executes code from string
	 * Based on mdn guide - https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/eval#Never_use_eval!
	 *
	 * @param {string} code some js code
	 * @example
	 *
	 * //global scope example
	 * const a = 10;
	 * const b = 10;
	 * const result = executor.execute('a+b'); //20
	 *
	 * @returns {*} any code result
	 */
	execute(code) {
		const func = `"use strict";return (function(args){ ${this.bindedObjectsStringCache} return (${code}); })`;

		/* eslint-disable no-new-func */
		return new Function(func)()(Object.values(this.bindedObjects));
		/* eslint-enable no-new-func */
	}

	/**
	 * {Object} all scopes added by bind()
	 *
	 * @private
	 */
	bindedObjects = {};

	/**
	 * {string} inner string code cached variables
	 *
	 * @private
	 */
	bindedObjectsStringCache = '';

	/**
	 * {number} objects counter cache
	 *
	 * @private
	 */
	bindedObjectsCountCache = 0;
}

export default CodeScriptExecutor;