wire and/or cola function to allow an arbitrary expression to be evaluated

cola.transform.expression.js

/** MIT License (c) copyright B Cavalier & J Hann */

(function (define, globalEval) {
define(function () {
"use strict";

	/**
	 * Creates a function that can be used to evaluate arbitrary expressions
	 * on a data item.
	 * @param options {Object}
	 * @returns {Function} function (value, item) {}
	 * @description
	 */
	return function createExpressionTransform (options) {
		return function expressionTransform (value, item) {
			try {
				return globalEval.call(options.expression, value, item);
			}
			catch (ex) {
				return ex.message;
			}
		}
	};

});
}(
	typeof define == 'function'
		? define
		: function (factory) { module.exports = factory(); },
	function (value, item) {
		// the only variables in scope are value, item, and any globals.
		// we have to cast to string because of "oddities" between
		// `eval` and `this`.
		return eval('' + this);
	}
));

examples.js

curl(['cola/transform/expression'], function (expression) {

console.log(expression(0.5, {}, { expression: "value * 100 + '%'" }));

console.log(expression(1330804406919, {}, { expression: "new Date(value)" }));

var item = { firstName: 'Ralph', lastName: 'Emerson' };
console.log(expression('whatevs', item, { expression: "item.firstName + (item.middleName ? ' ' + item.middleName : '') + ' ' + item.lastName" }));

});

// hypothetical usage:
{
	bindings: {
		dob: { expression: "new Date(value)" },
		displayName: { expression: "item.firstName + (item.middleName ? ' ' + item.middleName : '') + ' ' + item.lastName" }
	}
}

//The downside? It allows stuff like this:

"$('.allMyNodes')"; // access to other dom nodes
"dojo.date.locale.format(value)"; // access to globals
"item.otherProp = value * 100; value;"; // side-effects, non-deterministic behavior