# Checklist of Fix Bug

By [Dantc](https://paragraph.com/@dantc) · 2022-07-06

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1.  if the expression or variable is null, it’s still work;
    
2.  check the variable’s type and caller function belong to the varable;
    
3.  if you are not understand the original code immediately, but you understand after your deep thinking, write comment about it;
    
4.  incomming params check;
    
5.  return value maybe default value or just null, especially return empty object.

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*Originally published on [Dantc](https://paragraph.com/@dantc/checklist-of-fix-bug)*