Javascript Variable Scope Confusion

Question

In the following code snippet I've declared the variable "id" within the submit function. I attempt to assign a value to it within a nested function but it doesn't appear to be within scope and I don't know why.

$(document).ready(function() {
if (typeof(localStorage) == 'undefined' ) {
    alert('Your browser does not support HTML5 localStorage. Try upgrading.');
} 
else {

    $("#logForm").submit(function(){
        var id;

        chrome.bookmarks.getRecent(1, function(mostrecent) {
            getLastId(mostrecent);
            });

        function getLastId(mostrecent) {
            mostrecent.forEach(function(mostrecent) {
                lastId = mostrecent.id;
                alert(lastId + ' was last id');
                id = lastId;
                })
            }
        alert(id + ' outside function');

Bonus Question - If you know a better way to pull the last-used id from chrome for a bookmark would love to know what it is. I had to pull recent which doesn't account for the possibility of an added and then deleted last bookmark which would have incremented the index.

@ Šime - Is there a lint for ECMA 5?

Korak
– Korak

2011-04-09 22:24:54 +00:00
Commented Apr 9, 2011 at 22:24 — Korak
– Korak, Commented Apr 9, 2011 at 22:24
JSLint is for EcmaScript 5, too.

Šime Vidas
– Šime Vidas

2011-04-09 22:30:32 +00:00
Commented Apr 9, 2011 at 22:30 — Šime Vidas
– Šime Vidas, Commented Apr 9, 2011 at 22:30
You forgot to declare the lastId variable.

Šime Vidas
– Šime Vidas

2011-04-09 22:33:44 +00:00
Commented Apr 9, 2011 at 22:33 — Šime Vidas
– Šime Vidas, Commented Apr 9, 2011 at 22:33
missing semicolon on the forEach.

Eric Turner
– Eric Turner

2012-01-07 14:58:32 +00:00
Commented Jan 7, 2012 at 14:58 — Eric Turner
– Eric Turner, Commented Jan 7, 2012 at 14:58

Šime Vidas · Accepted Answer · 2012-01-07 13:01:02Z

2

This should do it:

$("#logForm").submit(function() {

    var id;

    chrome.bookmarks.getRecent(1, function(arr) {
        id = arr.pop().id;
    });

    // do stuff with id

});

edited Jan 7, 2012 at 13:01

answered Apr 9, 2011 at 22:37

Šime Vidas

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9 Comments

Korak Over a year ago

Thank you for noticing that. I'm struggling with the asynchronous functions required by the chrome api quite a bit. Do you know how to verify the value assignment has been made before attempting to use the variable?

Šime Vidas Over a year ago

@Korak If the callback is asynchronous, you have to continue your code inside the callback body. If the callback is synchronous, your can continue your code below the callback. So it depends...

Korak Over a year ago

@Šime Maybe I'm going about this the wrong way somehow. My goal is to get the id on the last node from the chrome bookmarks api which requires the usage of an asynchronous function. Is there a better way to assign, pass, or return that value than what I am doing?

Korak Over a year ago

@Šime just thought I would post to let you know that I've been able to move enough of the action inside the function to make it work. Thanks for the help!

Korak Over a year ago

@Šime Thanks a lot for all your help. Will be dealing with these issues on an ongoing basis so your answer will help with a bunch of variable extractions.

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