The first form that you list works, since it will evaluate a string at the end of delay. Using eval() is generally not a good idea, so you should avoid this. The second method doesn’t work, since you immediately execute a function object with the function call operator (). What ends up happening is that … Read more
You can always use global variables by accessing them as properties of the window object, like window.globalVar (though using globals is indeed not a good practice), so no, I don’t think there is ever a good reason to use the deprecated syntax. It is probably allowed for historical reasons: as Felix Kling mentioned, the original … Read more
It’s not supposed to be particularly accurate. There are a number of factors limiting how soon the browser can execute the code; quoting from MDN: In addition to “clamping”, the timeout can also fire later when the page (or the OS/browser itself) is busy with other tasks. In other words, the way that setTimeout is … Read more
Just to add to what everyone else have said about setTimeout: If you want to call a function with a parameter in the future, you need to set up some anonymous function calls. You need to pass the function as an argument for it to be called later. In effect this means without brackets behind … Read more
Update (2017) Here in 2017, Promises are built into JavaScript, they were added by the ES2015 spec (polyfills are available for outdated environments like IE8-IE11). The syntax they went with uses a callback you pass into the Promise constructor (the Promise executor) which receives the functions for resolving/rejecting the promise as arguments. First, since async … Read more
I think that 10 will be the most reliable minimum in all browser, since I’ve seen a lot of codes using it. However, 4ms is the minimum for HTML5 In fact, 4ms is specified by the HTML5 spec and is consistent across browsers released in 2010 and onward. Prior to (Firefox 5.0 / Thunderbird 5.0 … Read more
You have a choice of with or without webWorkers: Without WebWorkers For code that needs to interact with the DOM or with lots of other state in your app, you can’t use a webWorker so the usual solution is to break your work into chunks do each chunk of work on a timer. The break … Read more
As you give the function to the setTimeout in that form, the function is executed instead of passed to the setTimeout. You have three alternatives to make it work: Give first the function, then the timeout and the parameters as the last arguments: setTimeout(doRequest, proxytimeout, url, proxys[proxy]); Or just write a string that will be … Read more
Using setInterval or setTimeout You should pass a reference to a function as the first argument for setTimeout or setInterval. This reference may be in the form of: An anonymous function setTimeout(function(){/* Look mah! No name! */},2000); A name of an existing function function foo(){…} setTimeout(foo, 2000); A variable that points to an existing function … Read more
I recently asked about this and it is behaviour by design. When a tab is inactive, only at a maximum of once per second the function is called. Here is the code change. Perhaps this will help: How can I make setInterval also work when a tab is inactive in Chrome? TL;DR: use Web Workers.