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Start your free trialHayden Lau
4,186 PointsWhy did we need "return" before callback(data) in xhr.onload
For the below code, why do we need to have "return" before callback(data)?
xhr.onload = () => {
if(xhr.status === 200) {
let data = JSON.parse(xhr.responseText);
return callback(data);
}
};
I tired removing return and it worked exactly the same way.
Below is teh full code.
Thanks in advance.
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');
// Make an AJAX request
function getJSON(url, callback) {
const xhr = new XMLHttpRequest();
xhr.open('GET', url);
xhr.onload = () => {
if(xhr.status === 200) {
let data = JSON.parse(xhr.responseText);
return callback(data);
}
};
xhr.send();
}
function getProfiles(json) {
json.people.map( person => getJSON(wikiUrl + person.name, generateHTML));
}
// Generate the markup for each profile
function generateHTML(data) {
const section = document.createElement('section');
peopleList.appendChild(section);
section.innerHTML = `
<img src=${data.thumbnail.source}>
<h2>${data.title}</h2>
<p>${data.description}</p>
<p>${data.extract}</p>
`;
}
btn.addEventListener('click', (event) => {
getJSON(astrosUrl, getProfiles);
event.target.remove();
});
1 Answer
Diego Alvarez
6,680 PointsWithout the return, it doesn't print the astronauts on the page, at least that's what happens in my case.