如何在所有页面上都可以访问的内容脚本中创建变量

Question

I have a content script in which there is a script called myscript.js, now I have made it in such a way that if a page on google.com loads then setA of modifications are done otherwise setB of modifications are done. Now I want a variable which is accessible from all the webpages that open on that browser. like we have static variables in java, the same variable is accessible to all the objects of the class, using that analogy here the static variable is the global variable and objects are webpages that load

Answer 1

If you need something available in every instance of content scrips (and other extension pages too), you can use chrome.storage API .

A slight downside is that the API is asynchronous:

var myValue;
chrome.storage.local.get({myKey: "myDefault"}, function(data) {
  myValue = data["myKey"];
  // You can use myValue here..
});
// ..but not here

This is fine if you're okay with chaining asynchronous code; otherwise, you can maintain a local copy and update it on onChanged instead of using get every time:

  chrome.storage.onChanged.addListener(function(changes, area) {
    if(area == "local" && changes["myKey"]) {
      myValue = changes["myKey"].newValue;
    }
  });