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I have the following code:
var Panel = React.createClass({
getInitialState: function () {
return {
user_id: null,
blogs: null,
error: false,
error_code: '',
error_code: ''
};
},
shouldComponentUpdate: function(nextProps, nextState) {
if (nextState.error !== this.state.error ||
nextState.blogs !== this.state.blogs ||
nextState.error_code !== this.state.error_code
) {
return true;
}
},
componentDidMount: function() {
var self = this;
var pollingInterval = setInterval(function() {
$.get(self.props.source, function(result) {
if (self.isMounted()) {
self.setState({
error: false,
error_code: '',
error_message: '',
blogs: result.user.blogs,
user_id: result.user.id
});
}
}.bind(self)).fail(function(response) {
self.setState({
error: true,
error_code: response.status,
error_message: response.statusText
});
}.bind(self));
}, 1000);
},
render: function() { ... }
});
The important part to focus on is the componentDidMount This will fetch every second, regardless if there is an error or not. The render function, assuming theres an error, will display the appropriate method. So for all intense and purpose, this code does exactly what I want it to do, it fetches, if it fails, it fetches again until it succeeds.
But I need to make some changes, and this is where I am lost. I want to say: Fetch once, pass or fail - it doesn't matter. THEN every 15 seconds after that initial fetch, try again - regardless of pass or fail
I would normally spin up a backbone collection and router along with a poll helper to do all this, but in this specific case there is no need for the extra overhead. So thats where I am stumped. How do I accomplish what I am trying to achieve?
540
Let's explore how to use setInterval in React. The TL;DR: useEffect(() => { const interval = setInterval(() => { console. log('This will run every second!'
js import React from 'react'; import { useState } from 'react'; const Timer = () => { const [days, setDays] = useState(0); const [hours, setHours] = useState(0); const [minutes, setMinutes] = useState(0); const [seconds, setSeconds] = useState(0); const deadline = "December, 31, 2022"; const getTime = () => { const ...
The setTimeout method allows us to run a function once after the interval of the time. Here we have defined a function to log something in the browser console after 2 seconds. const timerId = setTimeout(() => { console. log('Will be called after 2 seconds'); }, 2000);
Using setInterval() We can pass an API call inside the setInterval() to make it run repeatedly. const res = await fetch(`https://jsonplaceholder.typicode.com/posts`); }, 2000); Once this interval is created, it will send the API request after every two seconds.
You should be able to just refactor your code a bit to be able to call your polling function a few different ways (like manually for example and then at a specified interval):
componentDidMount: function() {
this.startPolling();
},
componentWillUnmount: function() {
if (this._timer) {
clearInterval(this._timer);
this._timer = null;
}
},
startPolling: function() {
var self = this;
setTimeout(function() {
if (!self.isMounted()) { return; } // abandon
self.poll(); // do it once and then start it up ...
self._timer = setInterval(self.poll.bind(self), 15000);
}, 1000);
},
poll: function() {
var self = this;
$.get(self.props.source, function(result) {
if (self.isMounted()) {
self.setState({
error: false,
error_code: '',
error_message: '',
blogs: result.user.blogs,
user_id: result.user.id
});
}
}).fail(function(response) {
self.setState({
error: true,
error_code: response.status,
error_message: response.statusText
});
});
}
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