How i can do a function who can be applied to any variables at the end of the variable?

Question

I'm trying to do a function like .split() or .replace() or .remove(), i think is like a prototype function, how i can make this example works:

this.logThis = function(a) {
  console.log("The " + this + "is cool like a " + a);
}

var food = "apple";
food.logThis("orange");

To get this Output:

> "The apple is cool like a orange"

Important: I need the most short code possibly, pure javascript, NO JQUERY

Answer 1

If you want to be able to call the function on a string, you'll need to extend the String prototype:

String.prototype.logThis = function(a) {
  console.log("The " + this + " is cool like a " + a);
}

var food = "apple";
food.logThis("orange");

This'll work, but you might want to alter it slightly to use a more modern JavaScript syntax:

String.prototype.logThis = function(a) {
  console.log(`The ${this} is cool like a ${a}`);
}

const food = "apple";
food.logThis("orange")

It is also worth pointing out that extending native objects is considered by many to be a bad practice (here's why), so you might rather alter your function to avoid this.

Here's one way of doing that:

const obj = {
  food: 'apple',
  logThis(a) {
    console.log(`The ${this.food} is cool like a ${a}`);
  }
}

obj.logThis("orange");