JavaScript indefinido usado com número, booleano ou nulo

// Arithmetic operation of undefined with number, boolean or null gives NaN

let result;

result = 4 + undefined;
console.log(result);  // NaN

result = 4 - undefined;
console.log(result);  // NaN

result = true + undefined;
console.log(result);  // NaN

result = null + undefined;
console.log(result);  // NaN
SAMER SAEID