Write conditional for a "city not found" error

Question

I'm studying and building a weather journal app for a project using openweathermap.

When I write a zip code that doesn't belong to the country of my API, the console logs "cod:404 message:city not found", but I don't know how to display this to the user. I know that I need to write a conditional with an alert (wrong zip code!) before my postData code but I'm stuck here...

function action(e){
    const postalCode = document.getElementById('zip').value;
    const feelings = document.getElementById('feelings').value;
    console.log(newDate);
 
    getTemp(baseUrl,postalCode, apiKey)
    .then(function (data){
         if(/*Message error*/){
            alert('Wrong zip code, try again!');
        }
        //Route
        postData('http://localhost:8000/addData', { date: newDate, temp: data.main.temp, feel: feelings})
    .then(function(){
        //User Interface
        updateUI()
        })    
    })
}

enter image description here

Answer 1

As the response is an object containing cod and message, you can check if (data.cod === 404) {
Then show your alert.
Note that you need to return; or put the postData in the else, otherwise it still would be executed after the alert shows

Problem with @Yehr59 's answer, is that the getTemp probably won't throw an error, therefore it doesn't reach the .catch function. So in the .then you can perform the check I mentioned above in this answer.

You would have something like this:

getTemp(baseUrl,postalCode, apiKey)
    .then(function (data){
         if(String(data.cod) === '404'){
            alert('Wrong zip code, try again!');
        } else {
            //Route
            postData('http://localhost:8000/addData', { date: newDate, temp: data.main.temp, feel: feelings})
        }

I also wrapped data.cod around String, so it's always a string. We can't compare

"404" === 404 // false

Edit: Another way is to modify your getTemp function so that it would throw an error if the response code is 404, then you know once the .then is called, it's successful, and if the .catch is called, you'll handling an error