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@zdychacek
Last active February 15, 2017 20:15
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Async calls with self implemented async function
'use strict';
function async (generator, callback) {
if (generator.constructor.name !== 'GeneratorFunction') {
throw new Error('Function async accept only generator function.');
}
function handleResult (result) {
let resultValue = result.value;
if (result.done) {
return callback(resultValue);
}
// handle promise, resp. any thenable
if (typeof resultValue.then === 'function') {
resultValue.then(function (data) {
handleResult(genInstance.next(data));
}, function (err) {
genInstance.throw(err);
});
}
// handle generator
else if (resultValue.constructor.name === 'GeneratorFunction') {
// TODO: handle errors from inner generators
async(resultValue, function (data) {
handleResult(genInstance.next(data));
});
}
// handle thunk
else if (typeof resultValue === 'function') {
resultValue(function (err, result) {
if (err) {
return genInstance.throw(err);
}
let args = resultValue;
// if there are more than two parameters, then slice first err param
if (arguments.length > 2) {
args = [].slice.call(arguments, 1);
}
handleResult(genInstance.next(args));
});
}
}
let genInstance = generator();
handleResult(genInstance.next());
}
function sleep (time) {
return function (callback) {
setTimeout(callback, time);
}
}
function sleepPromise (time) {
return new Promise(function (resolve, reject) {
setTimeout(resolve, time);
});
}
function* innerTask () {
yield sleepPromise(1000);
console.log(3);
yield sleepPromise(1000);
console.log(4);
}
async(function* () {
console.log(1);
yield sleep(1000);
console.log(2);
yield innerTask;
try {
throw new Error('My error');
}
catch (ex) {
console.log(`Error catched: "${ex.message}".`);
}
yield sleep(1000);
console.log(5);
return 'Terezka';
}, function (retValue) {
console.log(`Finished with value: "${retValue}".`);
});
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