如何修复函数在JS中未定义

Question

Porting a Chrome extension to Firefox.

// Changes extension icon on tab switch
browser.tabs.onActivated.addListener(async function (change) {
  var status = await currentStatus();
  browser.tabs.get(info.tabId, function (change) {
    if (!(status) || info.url.match(/https:\/\/url.com\/*/) == null) {
      browser.browserAction.setIcon({
        path: 'images/icon-19-disabled.png'
      });
    } else {
      browser.browserAction.setIcon({
        path: 'images/icon-19.png'
      });
    }
  });
});

// Changes extension icon on tab URL switch
browser.tabs.onUpdated.addListener(async function (change, tab) {
  var status = await currentStatus();
  if (tab.url == undefined) {
    return;
  }

  if (!(status) || tab.url.match(/https:\/\/url.com\/*/) == null) {
    browser.browserAction.setIcon({
      path: 'images/icon-19-disabled.png'
    });
  } else {
    browser.browserAction.setIcon({
      path: 'images/icon-19.png'
    });
  }
});

Debugger is spitting out 'change is undefined'

I've tried changing the function name to info, but the debugger throws out the same error.

Answer 1

Well if your js parser is telling you change is undefined

then thats exactly the problem. change is undefined. renaming it to info doesn't change a thing, unless you also have an object info , that you can acsess.

So the parser is exactly telling you whats wrong, is inside this line:

browser.tabs.get(info.tabId, function(change) {
if (!(status) || info.url.match(/https:\/\/url.com\/*/) == null) {

It tells you that info === undefined and of course you can't do something like undefined.tabId or undefined.url.match() . because there is no such Object variables or methods inside an undefined