parse.js

(function() {

	console.time('test');

	var noop = function() {

	};
	var strParse = function(str, cur_statements, cur_vars) {
		cur_vars = cur_vars || [];
		cur_statements = cur_statements || [];
		try {
			eval('(function(){' + cur_statements.join(';') + '; var result = ' + str + ';})()');
			return cur_vars;
		} catch (err) {
			var msg = err.message,
				var_name,
				nm = err.name;
			if (nm === 'ReferenceError') {
				var_name = msg.substr(0, msg.indexOf(' is not defined'));
				if (var_name === '') {
					throw new Error(msg + ' when parse template "' + str + '"');
				}
				cur_vars.push(var_name);
				cur_statements.push('var ' + var_name + ' = {}');
				return strParse(str, cur_statements, cur_vars);
			}
			if (nm === 'TypeError') {
				var this_method = msg,
					_index = msg.indexOf('has no method \'');
				if (_index === -1) {
					throw new Error(msg + ' when parse template "' + str + '"');
				}
				var mt = msg.substring(_index + 15, msg.length - 1);
				var_name = cur_vars[cur_vars.length - 1];
				cur_statements.push(var_name + '.' + mt + ' = noop');
				return strParse(str, cur_statements, cur_vars);
			}
			throw new Error(nm + ':' + msg + ' when parse template "' + str + '"');
		}
	};

	console.log(strParse('task_name.toLowerCase() + task_id + task_data'));

	console.timeEnd('test');

})();