Expected: When a variable is created using createGreetable it should have an additional property greet set by greetable(text). The usual string methods should still be callable on this variable.
What I Tried:
const greetablePrototype = {
greetable: function(greeting) {
this.greet = `${greeting}, ${ this.valueOf() }!`
}
}
function createGreetable(str) {
const result = new String(str);
Object.setPrototypeOf(result, greetablePrototype)
return result;
}
const t = new createGreetable("world");
t.greetable("hello");
console.log(t.greet);
console.log(t.length);Output:
hello, [object String]!
5
Expected Output:
hello, world!
5
You can extend the string class:
class Greetable extends String {
greet (greeting) {
return `${greeting}, ${this}!`;
}
}
const g = new Greetable('world');
g.greet('hello'); // hello, world!
g.length // 5
A few modifications to your code were needed to get it to work as intended:
this.length in the greetable prototype function to update the string length each time (remember this is a string object).const result line to this.greet in the constructor function, setting the prototype of this to the greetablePrototype as intended, then returning the instance of our object return this.const greetablePrototype = {
greetable: function(greeting) {
this.greet = `${greeting}, ${this.greet}!`
this.length = this.greet.length;
}
}
function createGreetable(str) {
this.greet = String(str);
Object.setPrototypeOf(this, greetablePrototype)
return this;
}
const t = new createGreetable("world");
t.greetable("hello");
console.log(t.greet);
console.log(t.length);