How to return value from jQuery function?

Question

I am trying to return value from jQuery function. Here is my function:

 $('#output').keypress(function (event){ 
    var keycode = (event.keyCode ? event.keyCode : event.which);
    if(keycode == '13'){
        var read_lines = $('#output').val().split("\n");

        return  read_lines[read_lines.length-1];

    } 
    });

and I want to save the value it return in another variable

var newRead = functionName(event);
alert (newRead);

How can I do this because I am not able to access function. Thanks in advance!

You can't return a value from inside the callback of an event handler and expect it to go anywhere useful. please explain the intended aim of the code for pointers on how to do it. — iCollect.it Ltd
– iCollect.it Ltd, Commented May 9, 2015 at 0:03

renakre · Accepted Answer · 2015-05-09 00:04:30Z

2

In event handlers, you should call other functions instead of returning a value. function(){} in your event handler is a callback function.

In your case, you can directly print them in the keypress event:

$('#output').keypress(function (event){ 
    var keycode = (event.keyCode ? event.keyCode : event.which);
    if(keycode == '13'){
        var read_lines = $('#output').val().split("\n");

        alert(read_lines[read_lines.length-1]);
    } 
});

Or you can do this:

$('#output').keypress(function (event){ 
    var keycode = (event.keyCode ? event.keyCode : event.which);
    if(keycode == '13'){
        var read_lines = $('#output').val().split("\n");

        MyFunction(read_lines[read_lines.length-1]);
    } 
});

function MyFunction(result){
      alert(result);
}

answered May 9, 2015 at 0:04

renakre

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3 Comments

orsina Over a year ago

thanks for your help @erkaner.I have tried the first version and now I tried the second but it does not function again in my case.Here is my demo(line 93) link.I am trying to implement the equivalent of cin function i c++ (read in my case).The reason why I want to retuen a value from the function above is that I want to add this value at variables +="pOut+='"+ value+"';".If I add the value inside the function I have the returned value at the end of s variable.(You can see it at the alert(s) window which is opened when you enter smth and click enter)

Michael Geary Over a year ago

@orsina - You have gotten two correct answers, listen to them. JavaScript does not work the way you wish it did. You have to work with the language in the way it actually operates. When you make any kind of asynchronous call, you can't just return a value from the function - it won't go anywhere. You have to use a callback function or equivalent as described in these two answers.

orsina Over a year ago

@Michael thanks. I am working with it now and trying to correct my xample in that way. I really see this answer are correct. Sory about forgetting to accept but I was forgoten after my real example

ashokd · Accepted Answer · 2015-05-09 00:05:02Z

1

In order to access your read value, you need function similar as below.

functionName(newRead){
   alert(newRead);
}
$('#output').keypress(function (event){ 
    var keycode = (event.keyCode ? event.keyCode : event.which);
    if(keycode == '13'){
        var read_lines = $('#output').val().split("\n");
         functionName(read_lines);
        //return  read_lines[read_lines.length-1];

    } 
    });

answered May 9, 2015 at 0:05

ashokd

3932 silver badges11 bronze badges

1 Comment

orsina Over a year ago

Thanks @askhokd. I explained my problem at the comment above. Can you please help me in this case?

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