string - How [1,2] + [4,5,6][1] = 1,25 in JavaScript -

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i got question interview,

[1,2] + [4,5,6][1]

javascript giving answer 1,25.

how it's happening? please explain clearly.

lets start last part , write more verbose

var arr   = [4,5,6]; var value = arr[1];

is same as

[4,5,6][1]

and arrays 0 based, gives 5, have

[1,2] + 5;

the first part equal to

[1,2].tostring(),

and returns string "1,2" because array converted string when trying use in expression that, arrays can't added numbers, , have

"1,2" + 5

concatenating strings numbers gives strings, , adding strings get

"1,25"

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