如果语句不起作用-Chrome扩展程序

Question

That is my code from my background.js:

 chrome.webNavigation.onCompleted.addListener(function(o) {
   chrome.tabs.executeScript(o.tabId, {
         file: "test.js"
   });
 }, {
   url: [
     {hostContains: 'google.com'}
   ]
 });

What I want now is an if statement right where the test.js gets called. Something like this:

If a == b then execute the line 'file: "test.js"' else do nothing

I tried this but it didn't work:

 chrome.webNavigation.onCompleted.addListener(function(o) {
   chrome.tabs.executeScript(o.tabId, {
         if (a == b) {
          file: "test.js"
        }

   });
 }

Anyone know what I'm doing wrong ? Thanks !

Answer 1

You can't use an if statement inside an object literal. That's simply not valid syntax. A possible solution would be to pass a different object based on the condition:

 chrome.webNavigation.onCompleted.addListener(function(o) {
   chrome.tabs.executeScript(o.tabId, (a == b) ? { file: "test.js"} : {});
 }

Answer 2

The second parameter of the executeScript function takes an InjectDetails https://developer.chrome.com/extensions/tabs#type-InjectDetails object, you can't put an if statement in there.

You can have the if statement return an object literal, such as

chrome.webNavigation.onCompleted.addListener(function(o) {
   chrome.tabs.executeScript(o.tabId, 
     if (a == b) return {
      file: "test.js"
     }
   );
}