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JAAFAR CHRAIBI1,775 Points
What happens if i add a new "var" each time i want to change the value of the variable ?
Steven Parker212,245 Points
A variable should only be declared once. If you use the keyword "var" on the same variable a second time, it is not proper programming. But duplicate variable declarations using "var" will not trigger an error, so you can "get away with it".
However, if you use the newer "let" keyword instead, it will cause an error.
Example:(Tested on windows 10):
var superhero = "Spider-Man"; superhero = "Venom"; The above content resulted in file-size of 51 bytes.
var superhero = "Spider-Man"; var superhero = "Venom"; The above content resulted in file-size of 55 bytes.
Extra 4 bytes will not cause much of issue, but if you adapt this practice and write large js files, then there will be a significant difference in file-size.
In programing, it is not recommended to declare the same variable every time using 'var'. However, it does not give any error if you use 'var' again for the same variable but it's not a good practice.