Asynchronous JavaScript is a technique to load JavaScript asynchronously using async and defer attributes or script tag injection. Not to be confused with AJAX.
Questions tagged [asynchronous-javascript]
164 questions
18
votes
5 answers
Two different ways of putting the script at the bottom - what are the differences?
What are the differences between the two solutions below ?
In particular, is there a good reason to favour 2 over 1. (note: Please assume the name of the script to load is known. The question is just about if there is value in creating a minimal…
Zo72
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14
votes
1 answer
Why use `URL.createObjectURL(blob)` instead of `image.src`?
Q1. In the context of asynchronous JavaScript and the need to ‘fetch’ data from the client-side, why can’t we just edit our image elements by its attribute src?
Q2. Why is the Blob conversion process necessary to go through?
Q3. What is the blob…
hyfyline
- 143
- 1
- 1
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4
votes
2 answers
Does the JS engine create a new microtask that will execute every handler chained together in a Promise object when resolve is invoked?
I recently encountered this question on Stack Overflow, asking about how the then method really works in JavaScript. The responder, Trincot, made the following comment:
The host will check which job queues have entries, giving precedence to job…
Toby Harnish
- 90
- 1
- 9
4
votes
1 answer
Chrome.runtime.onMessage returns "undefined" even when value is known for asynchronous response
In my code I have a content script which requests a cookie from the background script.
Even though I can print the cookie to the Dev Tool console, the message received from background script is always undefined.
Why?
Background script:
// listens…
HackingAndJiuJItsu
- 129
- 10
4
votes
0 answers
Redux saga: how to put a `yield put()` inside an event listener?
I'm using Redux saga and OneSignal in my React Native app. In my saga I have the following generator function:
function* getOneSignalIDs() {
try {
OneSignal.init(appID)
OneSignal.addEventListener('ids', (device) => {
…
gkeenley
- 6,088
- 8
- 54
- 129
4
votes
1 answer
Nodejs + Mongodb: find data after aggregation
I'm a new to Nodejs and MongoDB.
Here is a sample of my dataset:
{
'name': ABC,
'age':24,
'gender':male,
...
}
Generally speaking, what I want to do is to aggregate data before using them to find different data clusters.
To be specific, I…
Lixing Liang
- 457
- 1
- 6
- 11
4
votes
1 answer
Asynchronous java script loading is showing error
Asynchronous java script loading is showing the following error:
Attribute name "async" associated with an element type "script" must
be followed by the ' = ' character. + jsf
I found this in my JSF2.4 application which uses template file…
Valsaraj Viswanathan
- 1,473
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- 28
- 51
3
votes
2 answers
Async function passed as prop into React component causing @typescript-eslint/no-misused-promises error
I have the following asynchronous submitNewPatient function which is throwing @typescript-eslint/no-misused-promises error message from elint. Is it possible to adjust the function such that it removes this error?
const submitNewPatient = async…
WmelonMan
- 33
- 1
- 4
3
votes
4 answers
React hooks: how to detect when particular state variable has updated
Before React hooks, I would use componentDidUpdate(prevProps, prevState), and if I wanted to execute given code only when this.state.a had updated, I'd do
if (prevState.a !== this.state.a) {
<...>
}
How can I achieve the same thing in…
gkeenley
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3
votes
2 answers
How to wait my custom command finish, then executing remaining Cypress commands
I'm getting trouble with Cypress asynchronous mechanism. I have a custom command that is placed in this file
class HeaderPage {
shopLink = 'a[href="/angularpractice/shop"]'
homeLink = ''
navigateToShopPage() {
…
Hoang
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- 1
- 6
3
votes
1 answer
AWS SDK wait for asynchronous call to complete?
The AWS SDK documentation is not very clear about when/how/if asynchronous service calls can be made synchronous. For example, this page (https://docs.aws.amazon.com/sdk-for-javascript/v2/developer-guide/calling-services-asynchronously.html)…
aaa90210
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3
votes
4 answers
Passing a named function in Javascript
How do you pass a named function with parameters without calling it.
Right now the only solution I have seems like a hack but it is to pass an unnamed function that will call the named function.
callback(function(){foo(params);})
Is there a better…
Qasim Ahmed
- 197
- 1
- 10
3
votes
5 answers
Defer loading of JavaScript - Uncaught ReferenceError: $ is not defined
I use google code to defer loading javascript (google pages)
But I have some inline javascripts such as:
And this gives me:
Uncaught ReferenceError: $ is not…
Manic Depression
- 1,000
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2
votes
1 answer
How do I destructure an array wrapped in the Promise keyword in javascript?
I am trying to retrieve data from a PSQL table. And this is my code for that:
async function requestData() {
var selectQuery = `SELECT "fName", "lName", "phoneNumber", "eMail" FROM public."User"`;
const {rows} = await…
Dirghayu Joshi
- 29
- 5
2
votes
0 answers
executeScript() and executeAsyncScript() of javascriptExecutor interface is not behaving as expected
I know that executeScript() function of JavascriptExecutor interface in selenium requires no signalling mechanism and it executes javascript inside it as synchronous(single threaded).
While executeAsyncScript() function of JavascriptExecutor…
a Learner
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