JS judgment element is a number

VaR Each = _. Each = _. foreach = Function (OBJ, iterator, context ){ If (OBJ = Null ) Return ; If (Nativeforeach & obj. foreach === nativeforeach ){ OBJ. foreach (iterator, context ); } Else If (Obj. Length = + obj. Length ){ For ( VaR I = 0, L = obj. length; I <L; I ++ ){ If (Iterator. Call (context, OBJ [I], I, OBJ) === breaker) Return ; } } Else { For ( VaR Key In OBJ ){ If (_. Has (OBJ, key )){ If (Iterator. Call (context, OBJ [Key], key, OBJ) === breaker) Return ; } } } }; Only the last entry of the array is true. That is, only the number type A = + A is true. This method contains

If (obj. Length = + obj. Length) is equivalent to If (typeof obj. Length = 'number')