How do I assign value to outside variable from chrome API function?

Question

I am facing problem when I am assigning value of a variavle from outside of a chrome api like the example below.

Code:

var btnStatus;

chrome.runtime.sendMessage({jsBlocker: "check"}, function(response) {
 btnStatus = response.data;
});

alert(btnStatus );

Output:

Output

Michael Radionov · Accepted Answer · 2015-02-26 09:19:40Z

2

sendMessage is asynchronous, which means that it will execute a passed callback only when it's ready, so it will take some time for a statement btnStatus = response.data; to happen. Again, because it is asynchronous the code below won't wait for sendMessage and will continue to run, as a result alert will show you the initial value of the btnStatus which is undefined. All your code which uses the data from response is dependent on this callback. You could put an alert inside the callback to test a coming data and then do desired stuff with it:

chrome.runtime.sendMessage({jsBlocker: "check"}, function(response) {
 btnStatus = response.data;
 alert(btnStatus);
});

answered Feb 26, 2015 at 9:19

Michael Radionov

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