If you need a large delay, there’s a chance that it may even crash things altogether. Maybe this code does exactly what you’re hoping for, but be aware that it has a large disadvantage: the loop will block JavaScript’s execution thread and ensure that nobody can interact with your program until it finishes. How to Write Better Sleep Function in JavaScript The loop will keep going while the difference between date and currentDate is less than the desired delay in milliseconds. In the loop it repeatedly gets the number of milliseconds which have elapsed since Januand assigns the value to the previously declared currentDate variable. It then creates an empty currentDate variable, before entering a do. It works by using the Date.now method to get the number of milliseconds that have elapsed since Januand assigning that value to a date variable. log ( 'World!' ) Īs expected, this will log “Hello”, pause for two seconds, then log “World!” log ( 'Hello' ) setTimeout ( ( ) => console. The standard way of creating a delay in JavaScript is to use its setTimeout method. Now that we have a better understanding of JavaScript’s execution model, let’s have a look at how JavaScript handles delays and asynchronous code. How to Use SetTimeout in JavaScript Properly If any of this is news to you, you should watch this excellent conference talk: What the heck is the event loop anyway? Rather, it will continue on its way, output “Hello!” to the console, and then when the request returns a couple of hundred milliseconds later, it will output the number of repos. It will not, however, wait for the request to complete. The JavaScript interpreter will encounter the fetch command and dispatch the request. This is because fetching data from an API is an asynchronous operation in JavaScript. If you run this code, it will output “Hello!” to the screen, then the number of public repos attributed to my GitHub account. a) Yes, it counts toward the time limit (so sleep (31) will trigger an error) b) It does the opposite of costing CPU performance - it lets other applications use the CPU (when an application sleeps, the CPU usage of that application will be near 0). Execution goes from top to bottom.Ĭontrast that with the equivalent JavaScript version: fetch ( '' ). It then parses the response, outputs the number of public repos attributed to my GitHub account and finally prints “Hello!” to the screen. Be sure to check browser support as this is a language feature introduced with ECMAScript 6. get (uri ) )Īs one might expect, this code makes a request to the GitHub API to fetch my user data. Here's a solution using the new async/await syntax. Understanding this is crucial for effectively managing time and asynchronous operations in your code.Ĭonsider the following Ruby code: require 'net/http' require 'json' Now that we’ve got a quick solution under our belts, let’s delve into the mechanics of JavaScript’s execution model. Using the sleep() function will be more practical when we get a large number of data.Understanding JavaScript’s Execution Model Here, we have only looped four times for the demonstration. In this way, we used the sleep() function to stop the request to the API for one second between each request. Next, print the API response and use the sleep(1) function to halt the data fetching for one second between successive requests. Next, create a $file variable and assign it with the file_get_contents() function with the $next_url as the parameter. The URL increments its suffix with 1 to get the successive API contents in the successive iterations. Assign the concatenation operation in the $next_url variable. Next, concatenate the $url with the iterator $i so that the URL becomes in the first iteration. Next, create a for loop that iterates the $i variable from 1 to 4. It reads the file and returns it as a string.įor example, create a variable $url and store the URL in it. The function takes a parameter $filename, a file, or a URL. We can utilize the file_get_contents() function to get the request from an API. In such a case, we can use the sleep() function to halt the consecutive request with a few seconds. When we continuously request large amounts of data, the server may get heavily loaded. We can use the sleep() function while requesting data from an API. Therefore, the second timestamp printed is 11:05:03, which has the five seconds difference from the previous one. Then, the sleep() function halts the program for five seconds. Here, the first timestamp printed is 11:04:58.
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