Find a javascript fix pattern

Question

I have many javascript files, one of which has code with an error and the other without.

How can I find the difference between them in order to find a pattern of fixing for all of them?   For example, if I have this source code: 

var x = whatever;
if (x === Nan) {//} 

eslint will throw an error saying use-isnan so to fix it, I have the target code: 

var x = whatever;
if (isNan(x)) {}