var label = prompt('Label for Vertical Line');
This code returns the value in label which I enter in the prompted field. But I want some time delay to get the prompted value.
I'm using this code:
var label=alertWithoutNotice();
function alertWithoutNotice(){
var lab;
setTimeout(function(){
lab=prompt('Label for Vertical Line');
}, 1200);
return lab;
}
But this doesn't return any value. Please tell me what is wrong?
This is a chronological issue. setTimeout schedules an asynchronous event. That means, until it runs, the rest of your script will continue to execute.
The result is your return lab line is executed before the timeout callback fires. And so on the return, lab is undefined at that point.
As such, you can't return values from asynchronous events, or at least not meaningfully.
Something like jQuery's deferred objects would be your best route to a fix here, but I don't know if jQuery is an option for you.
lab, because it doesn't have one until the callback fires.The problem is that you are returning value before get inside timeout because setTimeout function is asynchronous.
Take a look here to use synchronously: using setTimeout synchronously in JavaScript
Since you are dialing with asynchronous operation the simplest approach here is to use a callback function. For example:
alertWithoutNotice(function(label) {
alert(label)
});
function alertWithoutNotice(callback) {
setTimeout(function() {
callback(prompt('Label for Vertical Line'));
}, 1200);
}
So think of it is that alertWithoutNotice is notified when label is available. When it happens callback is invoked.
