CODEWITHSUNDEEP
javascript
Mauno Vähä
Mauno Vähä

Reputation: 9788

What's the difference when defining var as 0.5 compared to .5?

I'm curious, I have programmed JavaScript already few years but sometimes I get confused when I see the following variable declarations: (ofc. those could be any other numbers as well).

var exampleOne = 0.5;
var exampleTwo = .5;

What is the difference between these two, or is there any? Are there some sort of hidden benefits which I clearly don't understand?

Upvotes: 3

Views: 3001

Answers (2)

user2864740
user2864740

Reputation: 61935

There is no difference.

The Numeric Literals are parsed equivalently - that is, both 0.5 and .5 (as would .50) represent the same number. (Unlike most other languages, JavaScript has only one kind of number.)

I prefer to always include the [optional] leading 0 before the decimal.

Upvotes: 2

Felix Kling
Felix Kling

Reputation: 816790

To quote the specification:

0.5 matches the rule DecimalLiteral :: DecimalIntegerLiteral . DecimalDigits which is evaluated as (MV means mathematical value):

The MV of DecimalLiteral :: DecimalIntegerLiteral . DecimalDigits is the MV of DecimalIntegerLiteral plus (the MV of DecimalDigits times 10–n), where n is the number of characters in DecimalDigits.

.5 matches the rule DecimalLiteral :: . DecimalDigits which is evaluated as

The MV of DecimalLiteral :: . DecimalDigits is the MV of DecimalDigits times 10–n, where n is the number of characters in DecimalDigits.

So you can see that the only difference is that the value of the digits preceding the . are added to the final value. And adding 0 to a value doesn't change the value.

Upvotes: 4

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