How to set default boolean values in JavaScript?
boolean, javascript
Solution
You can do this:
this.hasWheels = hasWheels !== false;
That gets you a `true` value except when `hasWheels` is explicitly `false`. (Other falsy values, including `null` and `undefined`, will result in `true`, which I think is what you want.)
Problem
Setting default optional values in JavaScript is usually done via the `||` character ``` var Car = function(color) { this.color = color || 'blue'; }; var myCar = new Car(); console.log(myCar.color); // 'blue' var myOtherCar = new Car('yellow'); console.log(myOtherCar.color); // 'yellow' ``` That works because `color` is `undefined` and `undefined || String` is always the `String`. Of course that also works the other way around `String || undefined` is `String`. When two `Strings` are present the first one wins `'this' || 'that'` is `'this'`. It does NOT work the other way around as `'that' || 'this'` is `'that'`. The question is: How can I achieve the same with boolean values? Take the following example ``` var Car = function(hasWheels) { this.hasWheels = hasWheels || true; } var myCar = new Car(); console.log(myCar.hasWheels); // true var myOtherCar = new Car(false) console.log(myOtherCar.hasWheels); // ALSO true !!!!!! ``` For `myCar` it works because `undefined || true` is `true` but as you can see it does NOT work for `myOtherCar` because `false || true` is `true`. Changing the order doesn't help as `true || false` is still `true`. Therefore, am I missing something here or is the following the only way to set the default value? ``` this.hasWheels = (hasWheels === false) ? false: true ``` Cheers!