Array.length vs. array.length> 0

Question

Is there any difference between checking the length of the array as a plausible value and checking that it is> 0?

In other words, is there any reason to use one of these statements over another:

var arr = [1,2,3]; if (arr.length) { } if (arr.length > 0) { } 

Answer 1

array.length is the fastest and shortest than array.length > 0 . You can see the difference in their speeds: http://jsperf.com/test-of-array-length

if(array.length){...} is similar to if(0){...} or if(false){...}

Answer 2

Is there any difference between checking the length of the array as a plausible value and checking that it is> 0?

Since the value of arr.length can only be 0 or more, and since 0 is the only number that evaluates to false , there is no difference.

In the general case, Boolean(n) and Boolean(n > 0) give different results for n < 0 .

In other words, is there any reason to use one of these statements over another

Only reasons related to code readability and understanding, not behavior.

Answer 3

In javascript, they have no meaning.

In the end, anything between the if bracket will be evaluated as true or false.

For all possible false values, see All false values ​​in JavaScript

If you want to be more clear and explicit, use

 if (arr.length > 0) { } 

If you want to be less detailed, use

 if (arr.length) { }