1

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 :)

Pravissimo
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5 Answers5

7

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))
kind user
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6

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

Community
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baao
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  • Didn't know of the repeat function on javascript strings. That's the better solution probably. But why the heck would they ask for reimplementing an already existing function in the job interview :D – user3691763 Feb 28 '17 at 15:57
  • Well, who knows - they might just wanted to test if you know about that... But as written and linked above, don't use that pattern on native objects like String, Array, ... @user3691763 – baao Feb 28 '17 at 15:59
0
String.prototype.repeatify = function(amount)
{
  var endString = "";
  for(var i = 0; i < amount; ++i)
  {
    endString += this;
  }
  return endString;
}
user3691763
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0

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.

JeremiahB
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0

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"
xgqfrms
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