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`[1] == [1]` returns "false" and `[1] == 1` returns" true "?

I found this strange behavior in javascript

.

var v1 = [1];
var v2 = [1];

v1 == v2  // false

v1 == 1 //true

[1] == [1] // false

1 == [1]    // true

why does it [1] == [1]

return false

and [1] == 1

return true

?

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1 answer


spec says that if two operands ==

are of the same type of each other (for example, in the case [1] == [1]

where both of them are a type Object

), then ==

behaves exactly the same as ===

. These two arrays are not the same object, so it is returned false

. Note:

var v1 = [1];
var v2 = v1;

v1 == v2; // true


When the operands are of different types, they are both coerced. In the case, 1 == [1]

Rule 10 from the above link is applied first and the array is converted to the primitive that's it toString()

, which returns it '1'

. Then rule 6 (string '1'

to number conversion 1

) is applied and the comparison becomes 1 == 1

, and finally they are of the same type and are compared with ===

. Obviously 1 === 1

true.

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