The variable created in the jQuery event handler is not displayed [duplicate]

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Global variable is not passed to js 1 response

Hello!

Tell me, please, why the variable created in the handler does not extend beyond its limits?

For example, here will not produce anything:

$('#search').on('keyup', function(){ a = 'test'; }); alert(a); //ничего не выведет

And here it displays:

  $('#search').on('keyup', function(){ a = 'test'; alert(a); //окно test });

@Doofy I press the keys and apparently the handler that creates the variable should work.
Then this variable outside the brackets should be known by the idea
@DmitriySimushev, then global between documents, and this one in the stream
The deep reason is the misunderstanding of the asynchronous that is there, that

Accepted Answer · 2016-06-29T09:36:01

When the button is pressed, only the handler function works, the code which is written after - worked after the handler was created.

a does not exist before pressing the button. Initially, an alert is displayed, and then we press any button in #search and alert with the output of a already swallowing flash

 $('#search').on('keyup', function() { a = 'test'; console.log(a); // test }); console.log(a); // a is not defined

 $('#search').on('keyup', function() { a = this.value; f(a); }); function f(a) { console.log(a); }

 <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"> </script> <input id='search'>

You can declare a variable before the handler, assign a value to it in the handler, and then use it anywhere

 a = null; $('#search').on('keyup', function() { a = this.value; }); $('button').click(function() { console.log(a); });

 <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"> </script> <input id='search'> <button>получить значение</button>

I click on the keys and, in theory, the handler should work, which will create a variable.
Then this variable outside the brackets should be cleared, but not displayed
@Pavel, because when the button is pressed, only the handler functions work, the code that was written after - worked after the handler was created

The variable created in the jQuery event handler is not displayed [duplicate]

Reported as a duplicate by Dmitriy Simushev , aleksandr barakin , Streletz , user194374, zRrr Jun 30 '16 at 13:59 .

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