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Boolean Operators

The operators that return a Boolean value are: > : greater than >= : greater than or equals < : less than <= : less than or equals == : equals in evaluated value === : equals in value and type in : is a property of instanceof: is an object of


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console.log(3<3);   // falseconsole.log(3<=3);  // trueconsole.log(3==3);  // trueconsole.log(3===3); // true
   console.log(3==new Number(3));      // trueconsole.log(3===new Number(3));    // falseconsole.log(typeof 3);                        // numberconsole.log(typeof new Number(3));   // objectconsole.log(new Number(3)==new Number(3));    // falseconsole.log(new Number(3)===new Number(3));    // false

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function F(){this.x=100;}class C extends F{}var o = new C;console.log(o instanceof C);   // trueconsole.log(o instanceof F);   // trueconsole.log('x' in o);              // true

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To assign default values, the or operator(||) or the nullish coaslescing operator(??) can be used.


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const
   nullValue = null,
   numberValue = 300,
   zeroValue = 0,
   emptyValue = '',
   falseValue = false;console.log(nullValue || 'DEFAULT');       // DEFAULTconsole.log(numberValue || 'DEFAULT'); // DEFAULTconsole.log(zeroValue || 'DEFAULT');      // DEFAULTconsole.log(emptyValue || 'DEFAULT');   // DEFAULTconsole.log(falseValue || 'DEFAULT');     // DEFAULTconsole.log("........................");console.log(nullValue ?? 'DEFAULT');        // DEFAULTconsole.log(numberValue ?? 'DEFAULT');  // DEFAULTconsole.log(zeroValue ?? 'DEFAULT');       // 0console.log(emptyValue ?? 'DEFAULT');    // ''console.log(falseValue ?? 'DEFAULT');      // false

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