yield

yield

function xhr(callback) {
    console.log('now requesting...');
    setTimeout(function () {
        var response = {
            status: '200'
        };
        callback(response);
    }, 1000);
}

var generator;
var wrap = function (func) {
    var newFunc = function () {
        func(function (arg) {
            try {
                generator.send(arg);
            } catch(e) {
                console.log(e);
            }
        });
    };
    return newFunc;
}

var co = function (routine) {
    generator = routine();
    generator.next(); // start
};

co(function () {
    var resp = yield wrap(xhr)();
    console.log(resp);
    
    var resp2 = yield wrap(xhr)();
    console.log(resp2);
});