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JavaScript JavaScript Basics Storing and Tracking Information with Variables Introducing Variables

1,775 Points

What happens if i add a new "var" each time i want to change the value of the variable ?


4 Answers

Steven Parker
Steven Parker
212,245 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". :see_no_evil:

However, if you use the newer "let" keyword instead, it will cause an error.

Dinesh P
Dinesh P
415 Points

It won't result in an error. But using var every time is just an extra work 😄

Using "var" for declaring variable again and again will not result in error, but note it will increase the size of javascript file.

Example:(Tested on windows 10):

  1. var superhero = "Spider-Man"; superhero = "Venom"; The above content resulted in file-size of 51 bytes.

  2. 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.