Question

I have written a Chrome extension that adds a char counter to some input elements. There is no UI for this, it just injects the char counting code if the user is on a specific page.

There is a limit to how many chars should appear in the inputs. I initially wrote it to just display the number of chars but then I decided it would be nice if the user could choose to see how many chars they have left instead. So I decided to create an options page.

At some point in my options page I do this:

localStorage["count"] = count; // count is the string "countUp" or "countDown"

It turns out I can’t access the localStorage of options.html from the contentscript.js so I reluctantly created a background.html page which listens to requests from the contentscript and returns the localStorage values that the content script asks for.

In contentscript (simplified)

var countOption;

chrome.extension.sendRequest(
    {method: "localStorage", key: "count"},
    function(response){
        countOption = response.data;
        console.log(countOption); // returns "countUp"
    }
);

console.log(countOption); // returns undefined

if(countOption === "countUp") {
    doSomething();
} else {
    doSomethingElse();
}

Background page

<script type="text/javascript">
    chrome.extension.onRequest.addListener(
        function(request, sender, sendResponse) {
            if(request.method === "localStorage") {
                sendResponse({data: localStorage[request.key]});
            } else {
                sendResponse({});
            }
        }
    );
</script>

The problem is I can’t assign a value to countOption so that it is accessible in the scope of the rest of my script. When I assign it in the chrome.extension.sendRequest‘s response this is the window object so I have tried declaring countOption globally but it is still undefined in the rest of my script.

Can anyone see where I’m going wrong? Thanks.

Answer 1

Would something like this work?

function executeCount(countOption)
{
console.log(countOption); // returns undefined

if(countOption === "countUp") {
    doSomething();
} else {
    doSomethingElse();
}
}

chrome.extension.sendRequest(
    {method: "localStorage", key: "count"},
    function(response){
        executeCount(response.data);
    }
);