It accepts a function and a delay time in milliseconds. The setTimeout() function schedules code for the runtime to execute once a set amount of time has passed. Because of using promises, it is supported in ES6.Using setTimeout() to Wait for a Specific Time Theres a sleep method that simulates an asynchronous operation. This approach is preferred to delay a function. It runs in a single thread and since almost no function in Node performs direct I/O. Use the await() Keyword to Pause Execution of Codes in Node.js. Then, after the delay of 2 seconds, the text 'End' will be displayed on the screen. Initially, some of the statements are displayed on the screen. We are also using the then() method, which executes the required function after the completion of the promise. The setTimeout() function executes code after the specified amount of time. Here, we are creating a promise with the setTimeout() function. The loop will iterate 10 times with a pause of 2 seconds on every iteration. Return new Promise(resolve => setTimeout(resolve, milliseconds)) Īfter the execution of the above code, the output will be -Īfter two seconds, the output will change. That means if I make multiple requests to a node.js server, it won't spawn a new thread for each request but will execute each request one by one.

How to use sleep function in JavaScript?īefore implementing the sleep function in JavaScript, it is important to understand the execution of the JavaScript code. As per Understanding the node.js event loop, node.js supports a single thread model. Async/await functions help us to write the code in a synchronous manner. Because of this asynchronous behavior, it continues its work and does not wait for anything during execution. The behavior of JavaScript is asynchronous, so there is a concept of promises to handle such asynchronous behavior. js there are two types of threads: one Event Loop (aka the main loop, main thread, event thread, etc.), and a pool of k Workers in a Worker Pool (aka the. The await is used to wait for a promise and can only be used in an async function. The features such as promises and async/await function in JavaScript helped us to use the sleep() function in an easier way. We can use some approaches for simulating the sleep() function in JavaScript. Unlike other languages, JavaScript doesn't have any sleep() function. Java has a thread.sleep(), python has time.sleep(), and GO has time.sleep(2*cond). The programming languages such as PHP and C has a sleep(sec) function to pause the execution for a fixed amount of time.

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