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Start your free trialJoshua Ouma
20,865 PointsWhat is wrong with my code? Someone help
TypeError: Cannot read property 'source' of undefined at promises.js:35 at Array.map (<anonymous>) at generateHTML (promises.js:31) Below is my code:
const astrosUrl = 'http://api.open-notify.org/astros.json';
const wikiUrl = 'https://en.wikipedia.org/api/rest_v1/page/summary/';
const peopleList = document.getElementById('people');
const btn = document.querySelector('button');
function getJSON(url) {
return new Promise((resolve,reject)=>{
const xhr = new XMLHttpRequest();
xhr.open('GET', url);
xhr.onload = () => {
if(xhr.status === 200) {
let data = JSON.parse(xhr.responseText);
resolve(data);
}else{
reject(Error(xhr.statusText));
}
xhr.onerror = reject(Error("A network error occured"));
};
xhr.send();
});
}
function getProfiles(json) {
const profile = json.people.map( person => {
return getJSON(wikiUrl + person.name);
});
return Promise.all(profile);
}
function generateHTML(data) {
data.map( person =>{
const section = document.createElement('section');
peopleList.appendChild(section);
section.innerHTML = `
<img src=${person.thumbnail.source}>
<h2>${person.title}</h2>
<p>${person.description}</p>
<p>${person.extract}</p>
`;
});
}
btn.addEventListener('click', (event) => {
event.target.textContent = "Loading...";
getJSON(astrosUrl)
.then(getProfiles)
.then(generateHTML)
.catch(err => {
peopleList.innerHTML = "<h3>Something went wrong</h3>";
console.log(err)
})
.finally(event.target.remove());
});
2 Answers
Phil Wood
4,379 PointsHi Joshua,
The error is caused by 'thumbnail' not being defined. You are referencing a property that doesn't exist.
<img src=${person.thumbnail.source}>
The json you are sourcing from combining your two Urls is returning data - some of which do not contain 'thumbnail' You will have to put in a condition to test to see if the data is defined before trying to use it.
Brendan Moran
14,052 PointsTo troubleshoot this, use console.log(data)
to see what you are dealing with before the error occurs. Put it in the first line of the generateHTML
function. You might see that one of the profiles failed to come back from wikipedia. If that's the case, look at some of the other questions and answers on this video that deal with that problem.
Phil Wood
4,379 PointsPhil Wood
4,379 PointsYou could use something like this :