Javascript function doesn't return anything - Stack Overflow

admin管理员组

文章数量:1023744

My javascript function doesn't return anything. I really don't get it. Is it a problem of variable scope?

function getLanguage(){
    navigator.globalization.getLocaleName(
        function(locale){
            var lan = locale.value;
        },
        function(){
            var lan = null;
        }
    );
    return lan;
}

Thank you!

My javascript function doesn't return anything. I really don't get it. Is it a problem of variable scope?

function getLanguage(){
    navigator.globalization.getLocaleName(
        function(locale){
            var lan = locale.value;
        },
        function(){
            var lan = null;
        }
    );
    return lan;
}

Thank you!

• javascript
• function

Share Improve this question Follow asked Dec 21, 2014 at 20:28 DescampsAuDescampsAu 1,06622 gold badges1010 silver badges2929 bronze badges 3

• 3 Yes, scope is the issue. Define lan before navigator.globalization.getLocaleName – Neil Turner Commented Dec 21, 2014 at 20:31
• It is returning lan; did you check to see what its value is? – Scott Hunter Commented Dec 21, 2014 at 20:33
• If you want to avoid callback-soup use Promises: developer.mozilla/en/docs/Web/JavaScript/Reference/… – Halcyon Commented Dec 21, 2014 at 20:43

Add a ment  | 

1 Answer 1

Sorted by: Reset to default 4

This is a duplicate of the old asynchronicity problem, but there's a second issue as well -- scope.

First of all, scope. The lan variable is defined inside the internal function, and so cannot be seen from outside.

function getLanguage(){
    var lan;
    navigator.globalization.getLocaleName(
        function(locale){
            lan = locale.value;
        },
        function(){
            lan = null;
        }
    );
    return lan;
}

That was easy. But it still won't work, due to asynchronity. You have to set up your function to use a callback instead:

function getLanguage(callback){
    navigator.globalization.getLocaleName(
        function(locale){
            callback(locale.value);
        },
        function(){
            callback(null);
        }
    );
}

Also, by now, we don't even need the variable, so i got rid of it.

Then, you call it as:

getLanguage(function(lan){
    // something with lan here
});

My javascript function doesn't return anything. I really don't get it. Is it a problem of variable scope?

function getLanguage(){
    navigator.globalization.getLocaleName(
        function(locale){
            var lan = locale.value;
        },
        function(){
            var lan = null;
        }
    );
    return lan;
}

Thank you!

My javascript function doesn't return anything. I really don't get it. Is it a problem of variable scope?

function getLanguage(){
    navigator.globalization.getLocaleName(
        function(locale){
            var lan = locale.value;
        },
        function(){
            var lan = null;
        }
    );
    return lan;
}

Thank you!

• javascript
• function

Share Improve this question Follow asked Dec 21, 2014 at 20:28 DescampsAuDescampsAu 1,06622 gold badges1010 silver badges2929 bronze badges 3

• 3 Yes, scope is the issue. Define lan before navigator.globalization.getLocaleName – Neil Turner Commented Dec 21, 2014 at 20:31
• It is returning lan; did you check to see what its value is? – Scott Hunter Commented Dec 21, 2014 at 20:33
• If you want to avoid callback-soup use Promises: developer.mozilla/en/docs/Web/JavaScript/Reference/… – Halcyon Commented Dec 21, 2014 at 20:43

Add a ment  | 

1 Answer 1

Sorted by: Reset to default 4

This is a duplicate of the old asynchronicity problem, but there's a second issue as well -- scope.

First of all, scope. The lan variable is defined inside the internal function, and so cannot be seen from outside.

function getLanguage(){
    var lan;
    navigator.globalization.getLocaleName(
        function(locale){
            lan = locale.value;
        },
        function(){
            lan = null;
        }
    );
    return lan;
}

That was easy. But it still won't work, due to asynchronity. You have to set up your function to use a callback instead:

function getLanguage(callback){
    navigator.globalization.getLocaleName(
        function(locale){
            callback(locale.value);
        },
        function(){
            callback(null);
        }
    );
}

Also, by now, we don't even need the variable, so i got rid of it.

Then, you call it as:

getLanguage(function(lan){
    // something with lan here
});

本文标签： Javascript function doesn39t return anythingStack Overflow