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JavaScript jQuery Basics (2014) Creating a Password Confirmation Form Perform: Part 1

Posted by Nikolay Komolov
Nikolay Komolov
23,033 Points

How to pass an argument to an event handler?

Hello everybody!

Help me, please. Is there a way to pass an argument to an event handler? Here is an example:

function printSmth(text) { console.log(text); }; $password.focus(printSmth('Hello World'));

?

The above code executes the function right away, so can it be overcome?

Thanks!

John Coolidge
John Coolidge
12,614 Points

Hello Nikolay,

I'm not quite sure what you mean. If you have the following function:

function printSmth(text) { 
    console.log(text); 
}; 

$password.focus(printSmth('Hello World'));

then the function should run when you focus on the $password. Could you elaborate a bit more please?

Nikolay Komolov
Nikolay Komolov
23,033 Points

Thanks for the reply. Yes, I meant that :) But because of the brackets on the event handler, the console prints out the text immediately after the page's loaded. And I can't figure out how to prevent this behavior..

1 Answer

Louis Otto
Louis Otto
23,264 Points

Hi Nikolay,

The reason your function is failing is because you're not assigning a function to focus; you're assigning the result of the execution of printSmth()

What you should be doing is this:

function printSmth(text) { 
    console.log(text); 
}

$password.focus(function() { printSmth('Hello World');} );

// expanded version with explanation

$password.focus(function() { // state that we are running a function on focus
    printSmth('Hello World'); // actually run the function
});

That should work!

Also, for best practise, don't put a semicolon after functions declared the 'classical' way. Only place a semicolon after variable-declared functions: http://stackoverflow.com/questions/1834642/why-should-i-use-a-semicolon-after-every-function-in-javascript

Nikolay Komolov
Nikolay Komolov
23,033 Points

Thanks for helping :) As I stated above, the issue is that this function executes once the page's loaded (because of the brackets)

Louis Otto
Louis Otto
23,264 Points

Nikolay Komolov Ah I see, just updated the function for you ;)

Nikolay Komolov
Nikolay Komolov
23,033 Points

Cool, how could I have not thought about this..?)) Thanks a lot!)

Peter Tomasiewicz
Peter Tomasiewicz
5,592 Points

Thanks, a great explanation to a good question :)