A missing "use strict" error is common when you use ESLint. There are 2 possible fixes to it:

  • add the statement “use strict” in double quotes as a first line in your JS file
    "use strict"
    //the rest of your JS code goes below
    // AND must be in a strict mode
  • add a custom ESLint rule (as a comment!) to ignore the missing “use strict statement”
    /*eslint strict: ["error", "never"]*/
    //the rest of your JS code goes below
    //AND can be in a non-strict mode

You should try the first solution and if you’re not sure why it doesn’t work, then you can disable the ESLint errors for missing strict mode.