Issue
As an individual, I need to chain queries that run on page load, but I am unsure if this is possible. I would like to know how to create a JavaScript function that can run on page load and chain my queries. Additionally, any resources or documentation on JavaScript Promises that could be helpful would be appreciated.
Resolution
To chain queries that run on page load, you can create a JavaScript function and set it to run on page load. Inside this function, you can use JavaScript Promises to chain your queries. Promises can be used to handle asynchronous requests, allowing you to ensure that one query completes before moving on to the next.
Here is an example function using Promises to chain queries:
function runQueries() {
fetch('/query1')
.then(response => {
// process response
return fetch('/query2');
})
.then(response => {
// process response
return fetch('/query3');
})
.then(response => {
// process response
console.log('All queries completed!');
})
.catch(error => {
console.error('Error:', error);
});
}
window.onload = runQueries();
In this example, the fetch method is used to make HTTP requests to a server with the path of each query. Each query is chained with a .then method, which processes the response from the previous query and returns a new fetch request for the next query. If an error occurs in any query, the .catch method is triggered to handle the error.
Finally, the runQueries function is assigned to window.onload to ensure it is called when the page loads. This will trigger the chain of queries to run sequentially, ensuring that each query is completed before moving on to the next.