Why Flow cannot call ReactDOM.render with document.getElementById(…)

Question

I was getting this error below in Flow type checking.

Cannot call ReactDOM.render with document.getElementById(...) bound to container because null [1] is
incomp         


        

Answer 1

While Cogell's answer is correct, I would argue to keep the code simpler and add an exception.

ReactDOM.render(
 
  
    
      
        
        
        
        
      
    
  
 , // $FlowIgnore
 document.getElementById("root")
);

Notice the "$FlowIgnore" comment

and then in your .flowconfig file add this to the "options" field:

suppress_comment= \\(.\\|\n\\)*\\$FlowIgnore