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I have two javascript functions
function one () { do something long... like writing jpgfile on disk } function two () { do something fast... like show the file } I call it (in jQuery) like this
one (); two (); Because function two needs the link file from function one, i need to be sure the execution is completed... so getting the function two in the callback of function one should be the trick.. but how to do that ?
note : I did put an alert ('aaa') between those two functions to let function one complete, and it worked fine... when the alert is commented (removed) nothing works anymore !
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Passing a function to another function or passing a function inside another function is known as a Callback Function. Syntax: function geekOne(z) { alert(z); } function geekTwo(a, callback) { callback(a); } prevfn(2, newfn);
A JavaScript callback is a function which is to be executed after another function has finished execution. A more formal definition would be - Any function that is passed as an argument to another function so that it can be executed in that other function is called as a callback function.
A callback is a function passed as an argument to another function. This technique allows a function to call another function. A callback function can run after another function has finished.
Yes. The print( ) function takes another function as a parameter and calls it inside. This is valid in JavaScript and we call it a “callback”. So a function that is passed to another function as a parameter is a callback function.
You only need to use a callback if you are doing something asynchronous, otherwise it doesn't matter how long something takes, the next function won't run until the first has finished.
A callback is just passing a function as an argument, and then calling it when done.
function one (callback) { do something long... like writing jpgfile on disk callback(); } function two () { do something fast... like show the file } one(two); Obviously, if you are doing something asynchronous, then you need something that will tell you when it is finished (such as an event firing).
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