Javascript simple delay code#
Note: if you need to repeatedly execute code after a specified delay, then setInterval is more suited to the job. SetTimeout is best used for everything else. For example, if you wanted to fade an image into view for one second, have it visible for five seconds, and then fade it out for a period of one second, you could do the following: $ ( 'img' ). There is no possibility to cancel the delay. The delay method is meant specifically for adding a delay between methods in a given jQuery queue. The makeTalk function is then executed by setTimeout with a delay of one second: function makeTalk ( animal ) animateDiv ( ) īut as mentioned, using requestAnimationFrame offers various advantages, such as allowing the browser to make optimizations and stopping animations in inactive tabs.Īnimation with requestAnimationFrame by SitePoint ( CodePen.įinally, I’d like to clear up any confusion between the use of the native JavaScript setTimeout function and jQuery’s delay method. In the following example, we select a random animal from an animals array and pass this random animal as a parameter to a makeTalk function. In a basic scenario, the preferred, cross-browser way to pass parameters to a callback executed by setTimeout is by using an anonymous function as the first argument. If you’ve defined an alternative setTimeout method which would be found and returned in priority in the scope chain, then you’ve probably got bigger problems to worry about.įor the purposes of this tutorial, I’ll omit window, but ultimately, which syntax you choose is up to you. In my opinion, this adds complexity for little or no benefit. Both setTimeout and tTimeout refer to the same function, the only difference being that in the second statement we are referencing the setTimeout method as a property of the window object. Well, when running code in the browser, scope would refer to the global window object. You’ll notice that sometimes syntax above tTimeout. Note: the square brackets denote optional parameters. , argN are additional arguments passed to the function specified by functionRef. delay is the number of milliseconds by which the function call should be delayed.code is an alternative syntax that allows you to include a string instead of a function, which is compiled and executed when the timer expires.functionRef is the function to be executed after the timer expires.scope refers to the Window interface or the WorkerGlobalScope interface.timeoutID is a numerical ID, which can be used in conjunction with clearTimeout to cancel the timer.Making our code much more clean and simple.From the MDN documentation, the syntax for setTimeout is as follows: const timeoutID = setTimeout (code ) const timeoutID = setTimeout (code, delay ) const timeoutID = setTimeout (functionRef ) const timeoutID = setTimeout (functionRef, delay ) const timeoutID = setTimeout (functionRef, delay ) The main advantage compared to the setTimeout method we explained before, is that we can re-use the delay function. If we combine the setTimeout function with promises, we can then create a more readable code and place our whole code inside the same (async) function. Note that Promises are part of the ES6 standard and won't work in some legacy browsers such as IE 11. Therefore, keep on reading! Wait using PromiseĪnother way to make an asynchronous wait with moder JavaScript is by using the Promise function. This will very probably be ok in any circumstance, and the solution to it can be as simple as placing the rest of the code inside the timeout too, but it is not something that can serve us in every scenario.Īlso, if you want to keep on adding delays inside the same delayed function, we can easily run into what is known as the callback hell (and that's not pretty). This means that anything defined after it on the code will run before the delay. Notice how our setTimeout function runs asynchronously and that it won't stop the flow of our program. log ( "Executed before the delay, but after the 1st console.log" ) Now, this looks great and simple! However, here's the trick: console. In this case, we are using 1000ms, which is the equivalent of 1 second. One is the callback function that will get executed after a specific time, and the other is the number of milliseconds we want to delay the execution. The setTimeout function takes two parameters. One of the easiest way to achieve a 1 second delay is by using the setTimeout function that lives on the window global object. Some are better than others and some should only be used in specific circumstances. There are quite a few ways to tell JavaScript to wait for 1 second. Im really struggling with this, but its probably very simple: I want to display an alert a short time after the field recieves focus. To force a 1 second pause or delay in JavaScript we can use the setTimeout function, but if we want a better solution we should use the Promise function.
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