How to trigger a anynomous function with parameters Javascript

Question

Today I was at job interview - and I had been presented with a task. I have never encoutered such a function, so there it is:

Write down a function which after triggering like this:

console.log('hello'.repeatify(3))

returns

hellohellohello

I was trying to create an empty object and append a method repeatify, however i just don't know how to trigger it just with 'hello'.

Maybe i should change console.log method?

Thanks for the help :)

Answer 1

Wasn't that really hard. You have to make a new function for String.prototype and use repeat() function to multiply given string by given argument.

 String.prototype.repeatify = function(count){ return this.repeat(count); }; console.log('hello'.repeatify(3))

Answer 2

You can create your own prototype methods for every object, but you shouldn't do it with native objects:

 String.prototype.repeatify = function(num) { return this.repeat(num); } console.log('hello'.repeatify(3));

read more about this bad practice here

Answer 3

String.prototype.repeatify = function(amount)
{
  var endString = "";
  for(var i = 0; i < amount; ++i)
  {
    endString += this;
  }
  return endString;
}

Answer 4

Just modify String's prototype object:

String.prototype.repeatify = function (A) {
   var i = 1;
   var a = this;
   while (i++ < A) {
      a += this;
   }
   return a;
}

console.log('hello'.repeatify(3));
// outputs hellohellohello

There are mixed feelings on modifying the prototype of built in objects. I have both that it is just fine and that it is a bad practice. Personally I try to avoid it and prefer defining a standalone function to modifying the prototype of something I didn't create.

Answer 5

ES6 version

repeatify

String.prototype.repeatify = String.prototype.repeatify || function (times = 1) {
  // ES5 this
  return [...``.padStart(times, ` `)].map((item, i) => item = this).join(``);
};

`abx`.repeatify(3);
// "abxabxabx"