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Is there a sleep function in JavaScript?
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javascript doesn't have these kinds of sleep functions. But we should thank promises and async/await function in ES 2018. Because these features have helped us to use sleep() as easy as possible. Let's discuss it in a nutshell.
To delay a function execution in JavaScript by 1 second, wrap a promise execution inside a function and wrap the Promise's resolve() in a setTimeout() as shown below. setTimeout() accepts time in milliseconds, so setTimeout(fn, 1000) tells JavaScript to call fn after 1 second.
To delay a function call, use setTimeout() function. functionname − The function name for the function to be executed. milliseconds − The number of milliseconds. arg1, arg2, arg3 − These are the arguments passed to the function.
If you are looking to block the execution of code with call to sleep, then no, there is no method for that in JavaScript.
JavaScript does have setTimeout method. setTimeout will let you defer execution of a function for x milliseconds.
setTimeout(myFunction, 3000); // if you have defined a function named myFunction // it will run after 3 seconds (3000 milliseconds) Remember, this is completely different from how sleep method, if it existed, would behave.
function test1() { // let's say JavaScript did have a sleep function.. // sleep for 3 seconds sleep(3000); alert('hi'); } If you run the above function, you will have to wait for 3 seconds (sleep method call is blocking) before you see the alert 'hi'. Unfortunately, there is no sleep function like that in JavaScript.
function test2() { // defer the execution of anonymous function for // 3 seconds and go to next line of code. setTimeout(function(){ alert('hello'); }, 3000); alert('hi'); } If you run test2, you will see 'hi' right away (setTimeout is non blocking) and after 3 seconds you will see the alert 'hello'.
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A naive, CPU-intensive method to block execution for a number of milliseconds:
/** * Delay for a number of milliseconds */ function sleep(delay) { var start = new Date().getTime(); while (new Date().getTime() < start + delay); } If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
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