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

Welcome to stackoverflow, please show us what have you tried and include a [mcve] — Sagiv b.g, Apr 29 '19 at 10:14
Why can't you make a function with two parameters that prints them into a statement? — Krishna Prashatt, Apr 29 '19 at 10:17
Yes, but my example is showing my bad code, thats why im tryng find a solution... — IchQuile, Apr 29 '19 at 10:17
Im looking for a structure like this: variable.andFunctionHere() — IchQuile, Apr 29 '19 at 10:18
I can do a function with two parameters, of course like this: function logThis(variable,a) {}; but i need the structure like .split() or .replace()... — IchQuile, Apr 29 '19 at 10:21

James Hibbard · Answer 1 · 2019-04-29T10:22:36.117

6

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");

edited Apr 29 '19 at 10:22

answered Apr 29 '19 at 10:16

James Hibbard

16,490
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Thanks for your answer, your code works fine!, i appreciate your answer... – IchQuile Apr 29 '19 at 10:22
1

No worries. If it helps, I'd be obliged if you could accept it as the answer. – James Hibbard Apr 29 '19 at 10:26
Can i replace the "String." to "Int." or "Object.", for apply the function to any type of variable? – IchQuile Apr 29 '19 at 10:31
Or maybe the String.prototype, automatically can be used for any type of variable, for example: var obj = { "name" : "chicken"}; obj.logThis("hen"); – IchQuile Apr 29 '19 at 10:37
Sorry, stepped away from the PC for a while, but it looks like you found your answer. – James Hibbard Apr 29 '19 at 12:26
You both have the answer, how i can decide? – IchQuile Apr 29 '19 at 12:33
It's just nice if you accept one of the answers, which you already did, so all good :) – James Hibbard Apr 29 '19 at 12:44
1

I appreciate your answer too, you have other methods... <3 – IchQuile Apr 29 '19 at 12:46
Can you give me a review of my Answer of this post?: https://stackoverflow.com/questions/55903412/using-onclick-on-span-elements/55903648#55903648 – IchQuile Apr 29 '19 at 12:49

score 2 · Accepted Answer · answered Apr 29 '19 at 10:18

2

I will preface this by saying that generally, you don't want to extend prototypes. For that I will refer you here.

However - if you really wanted to, you could:

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

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

answered Apr 29 '19 at 10:18

Tim VN

1,183
1
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19

Can i use a custom replacing of "String." with "Int" or "Object", for apply the function to any type of variable? – IchQuile Apr 29 '19 at 10:32
You might want to take a look at Classes: https://javascript.info/class – Tim VN Apr 29 '19 at 11:05
Thankyou, i already Works good, i replace with Number.prototype.LogThis(); using a example with intergers and works so nice... i can mix absolutly all with that... – IchQuile Apr 29 '19 at 11:08

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

2 Answers2