Check if a variable contains a numerical value in Javascript?

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What about: 

function isNumber(n){
    return typeof(n) != "boolean" && !isNaN(n);
}

The isNaN built-in function is used to check if a value is not a number.

Update: Christoph is right, in JavaScript Boolean types are convertible to Number, returning the 1 for true and 0 for false, so if you evaluate 1 + true the result will be 2.

Considering this behavior I’ve updated the function to prevent converting boolean values to its numeric representation.

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