Print the number of values as take from the Index value from array

Question

Recently Attended the interview, Some one asked the question like below:

var array = [0,1,2,3,4,5];

Output :

  temp:
    temp1:1
    temp22:22
    temp333:333
    temp4444:4444
    temp55555:55555

I tried below code it is working fine but is there any best solution for this example :

array.forEach(function(item,index){
      var text ="";
        if(index >= 2){
               for(var j =1; j <= index; j++){
               text += index;
               }
                console.log("temp"+text + ":" + text);
        }else{
        console.log("temp"+index + ":" + index);
        }
});

Thanks in advance!

VLAZ · Accepted Answer · 2016-11-30 18:36:18Z

1

Using ES6 template strings and String.prototype.repeat

var array = [0,1,2,3,4,5];

array.forEach(item => {
  const text = String(item).repeat(item);
  console.log(`temp${text}: ${text}`);
})

And the same code translated into ES5 - this will work in all browsers starting from IE9 and above.

var array = [0,1,2,3,4,5];

array.forEach(function(item) {
  var text = Array(item+1).join(item);
  console.log("temp" + text + ": " + text);
})

Since String.prototype.repeat does not exist in ES5, there is a bit of a hack to generate a string of specific length with repeating characters: Array(initialCapacity) will create a new array with empty slots equal to what number you pass in, Array.prototype.join can then be used to concatenate all members of the array into a string. The parameter .join takes is the separator you want, so, for example you can do something like this

var joinedArray = ["a","b","c"].join(" | ");

console.log(joinedArray);

However, in this case, each of the members of the array is blank, since the array only has blank slots. So, upon joining, you will get a blank string, unless you specify a separator. You can leverage that to get a repeat functionality, as you are essentially doing something like this

//these produce the same result
var repeatedA = ["","",""].join("a");
var repeatedB = Array(3).join("b");

console.log("'a' repeated:", repeatedA);
console.log("'b' repeated:", repeatedB);

Using the Array function, you can scale it to any number of repeats you want. The only trick is that you need to add 1 when creating the array, since you get one less character when joining.

edited Nov 30, 2016 at 18:36

answered Nov 30, 2016 at 17:42

VLAZ

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2 Comments

Siva Over a year ago

Hi @vlaz, Nice if you don't mine could explain me code how it will work in ES5, I am not getting ` Array(item+1).join(item);` Thank you so much in advance !

VLAZ Over a year ago

@Siva sure, let me edit the answer for better clarity

Nina Scholz · Accepted Answer · 2016-11-30 17:40:42Z

1

You could iterate the array and iterate the count. Then display the new string.

var array = [0, 1, 2, 3, 4, 5];

array.forEach(function (a, i) {
    var s = '';
    while (i--) {
        s += a;
    }
    console.log ('temp' + s + ':' + s);
});

answered Nov 30, 2016 at 17:40

Nina Scholz

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