Javascript error: missing = in destruction declaration

This is not a standard JavaScript error. This comes from your editor. You must use js2-mode (Javascript mode) for your Emacs editor. It might be the missing equivalent in the for loop. Example:

for(i 0; i < arr.length;i++); /* missing = in destructuring declaration */

      

        
        
        
      

    

However, without looking at your code, we can only guess.