A JavaScript object featuring a predefined value

Question

A JavaScript object featuring a predefined value

I have a simple goal that I'm unsure about achieving.

My objective is to create an object that will return a specific value if no property is specified. For example:

console.log(obj) // Should output "123"
console.log(obj.x) // Should output "ABC"

javascript

Answer 1

Answer №1

Implement a custom toString() method for your own object's prototype.

function CustomObject() {
}
CustomObject.prototype.toString = function () {
    return '123';
};
var myObj = new CustomObject();
myObj.property = 'ABC';
console.log(myObj + '');
console.log(myObj.property + '');

Answer 2

Implement a custom toString() method for your own object's prototype.

function CustomObject() {
}
CustomObject.prototype.toString = function () {
    return '123';
};
var myObj = new CustomObject();
myObj.property = 'ABC';
console.log(myObj + '');
console.log(myObj.property + '');

Answer 3

Answer №2

This method demonstrates utilizing Symbol's toPrimitive for achieving the desired outcome:

const mainColor = {
  normal: 'blue',
  darker: 'black',
  lighter: 'gray',
}

Object.defineProperty(mainColor, Symbol.toPrimitive, {
  value: () => mainColor.normal
});

This results in the following behavior:

console.log('main color: ' + mainColor.darker) // outputs "main color: black"
console.log('main color: ' + mainColor) // outputs "main color: blue"

Answer 4

This method demonstrates utilizing Symbol's toPrimitive for achieving the desired outcome:

const mainColor = {
  normal: 'blue',
  darker: 'black',
  lighter: 'gray',
}

Object.defineProperty(mainColor, Symbol.toPrimitive, {
  value: () => mainColor.normal
});

This results in the following behavior:

console.log('main color: ' + mainColor.darker) // outputs "main color: black"
console.log('main color: ' + mainColor) // outputs "main color: blue"

A JavaScript object featuring a predefined value

Answer №1

Answer №2

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