Does node.js support yield?

Question

Is there any way to get generators into node.js?

I\'m currently faking them with callbacks, but I have to remember to check the response of the callback inside of my gen

Answer 1

Apparently not in the current stable version. You can however achieve the same using node-fibers + promises.

Here is my implementation:

var fiber = require('fibers');

module.exports.yield = function (promise) {

    var currentFiber = fiber.current;
    promise
        .then(function (value) {
            currentFiber.run(value);
        })
        .otherwise(function (reason) {
            currentFiber.throwInto(reason);
        });

    return fiber.yield();
};
module.exports.spawn = function (makeGenerator) {
    fiber(function () {
        makeGenerator.apply(this, Array.prototype.slice.call(arguments, 1));
    }).run();
};

And a sample code on how it works: (query.find returns a promise)

        var generators = require('./utils/generators');
        var query = require('./utils/query');

        generators.spawn(function () {
            try {
                var field1 = generators.yield(query.find('user', { _id : '1' }));
                var field2 = generators.yield(query.find('user', { _id : '2' }));
                console.log('success', field1[0]._id, field2[0]._id);
            }
            catch (e) {
                console.error('error', e);
            }
        });