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Neil Bircumshaw
Full Stack JavaScript Techdegree Student 14,597 PointsTrying to save a functions data to a CSV file
So this is my JS code
getAllShirtDetailsAsync()
.then(function(data) {
console.log(data);
})
.catch(function(err) {
console.log(err);
});
var shirtInfo = getAllShirtDetailsAsync();
fs.mkdir('data',function(){
fs.writeFile('./data/t-shirtdata.csv', JSON.stringify(shirtInfo))
})
The getAllShirtDetailsAsync() gets details of a 8 different shirts in an array of objects, I then want to spit this array of objects containing the info into readable data in an CSV file. So I create a directory with fs.mkdir called data, then create a csv file within that directory, I then try to stringify the array of information with the variable called shirtInfo which relates to the function.
When I go into the data csv file all that comes up is "{}" an non of the data. Anybody know why this is?
2 Answers
Thomas Nilsen
14,957 PointsgetAllShirtDetailsAsync() is an async method, which means you can't do this:
var shirtInfo = getAllShirtDetailsAsync();
You need to do something like this:
getAllShirtDetailsAsync()
.then(function(data) {
//Do the csv-code here.
})
.catch(function(err) {
console.log(err);
});
or even structure it like this:
getAllShirtDetailsAsync()
.then(writeToCsv)
.catch(handleErr);
function writeToCsv(data) {
//write to csv
}
function handleErr(err) {
//error handling here
}
I still urge you to read about callbacks and promises, in order to get a better understanding of this.
I don't care if you used my code. What's important is that you learn from it and actually understand it :)
Neil Bircumshaw
Full Stack JavaScript Techdegree Student 14,597 PointsAnd what exactly is the different between a promise which is called and using a "Async function" that was introduced in ECMAScript 2017? Are they similar in nature?
Neil Bircumshaw
Full Stack JavaScript Techdegree Student 14,597 PointsNeil Bircumshaw
Full Stack JavaScript Techdegree Student 14,597 PointsDon't worry, I have been over several tutorials about promises and understood the concept for the most part, I can't actually just use something without understanding it, there would literally be no point, I want to learn rather than just use code in order to pass.
Although going through my understandings of promises, does a promise always return the value asynchronously? So it happens as soon as it able to do so and does not wait in line?
So the reason I can not save the asynchronous function is because the function may not have been processed and retrieved yet? Is this why you can't do it like this? Therefore the "then" keyword will act as the next step when the asynchronous data has finished? So it's saying "then do this". Please correct me if my understanding is wrong at any point here. Thank you Thomas so far, you've been a big help.