index 0 in the second level javascript arrays -


can please know why if second level entry in multidimensional javascript array returned undefined if level length equal 1 ?
example : 

arr = array(   array(1)  )

the following return unlikely result : undefined, while it's suppose 1 (or @ least that's expect be)

console.log(arr[0][0])

but when have more record in level (length>1) : 

arr = array(   array(1,2)  )

and try : console.log(arr[0][0]), returns 1 time.
explanation issue or why happening appreciated
thanks

you should consult documentation of array constructor:

arraylength
if argument passed array constructor integer between 0 , 232-1 (inclusive), returns new javascript array length set number.

array(1) not create array element 1, creates array of length 1 one element: undefined.

to have less ambiguous constructor, use array literal:

[[1]]

this 1 array contains 1 array contains value 1.


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