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javascriptoperator-precedence

Javascript OR Expression: return Operand that is *not* NaN

I have an OR expression that should return the operand that is anything else than NaN:

(1 || NaN) // evaluates to 1 
(NaN || 1) // evaluates to 1

But when the other operand is also a falsy value like 0, null, undefined or false, Javascript returns always the rightmost operand:

(0 || NaN) // evaluates to NaN
(NaN || 0) // evaluates to 0
// same for combinations of 0, null, undefined and false

Is there a way to fit the desired behaviour "Return the operand that is not NaN" into a nice & short expression or do I have to rely on an if/else construct?

Solution

  • You could add a default falsy value at the end of the expression, like

    result = yourValue0 || yourValue1 || 0;

    In this case, you get either a truthy value of yourValueX or the last falsy value.