Update 01_javascript_refresher.md

fixed misspelling on line 1727

... by using _let_ and _const_ you will *writ* (write) clean code and avoid hard to debug mistakes....

01_Day_JavaScript_Refresher/01_javascript_refresher.md

@@ -1724,7 +1724,7 @@ for (let i = 0; i < 3; i++) {
 // console.log(i), Uncaught ReferenceError: gravity is not defined
 ```
 
-The scope _let_ and _const_ is the same. The difference is only reassigning. We can not change or reassign the value of const variable. I would strongly suggest you to use _let_ and _const_, by using _let_ and _const_ you will writ clean code and avoid hard to debug mistakes. As a rule of thumb, you can use _let_ for any value which change, _const_ for any constant value, and for array, object, arrow function and function expression.
+The scope _let_ and _const_ is the same. The difference is only reassigning. We can not change or reassign the value of const variable. I would strongly suggest you to use _let_ and _const_, by using _let_ and _const_ you will write clean code and avoid hard to debug mistakes. As a rule of thumb, you can use _let_ for any value which change, _const_ for any constant value, and for array, object, arrow function and function expression.
 
 ### 7. Object