How to add a common string in every randomly generated string Javascript

Question

I am generating random strings using the below function in node.js. I wanted to know if there is any way to create text strings appropriately with a common string within every randomly generated string.

EDIT: The common string can be in any location of the generated string

For example:

Randomly generated string - Cxqtooxyy4

Can I add 'abc' or 'ABC' within that string like this - Cxqtoabcoxyy4 or CxqtoABCoxyy4 respectively.

My Code -

var randomTextArrayGeneration = function(size)
{
    var text = "";
    var possible = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
    for(var i=0;i<size;i++)
        text += possible.charAt(Math.floor(Math.random() * possible.length));
    return text;
}

Can anyone tell me how do I do this? Any help is really helpful.

Should the common string always be at the same position within the random string? What if the size specified is shorter than the common string? — nnnnnn
– nnnnnn, Commented May 28, 2016 at 21:53
A little unclear about your requirements. Does the embedded string need to be in the same location each time? Does it need to be in a random location each time? Does it not matter where it is? — Andrew Eisenberg
– Andrew Eisenberg, Commented May 28, 2016 at 21:53
Sorry didn't explain it properly. The embedded string can be in any location. — Dazzler
– Dazzler, Commented May 28, 2016 at 21:54
Can you...yes, of course. Shouldn't be hard to get an idea how by looking at the various substring/manipulation methods that are documented in numerous places on web and at least making an attempt — charlietfl
– charlietfl, Commented May 28, 2016 at 21:54
Any location? Then why not just place it at the end after generating a random string with length size -3 (assuming the fixed string is of length 3). — Andrew Eisenberg
– Andrew Eisenberg, Commented May 28, 2016 at 21:56

user5455540 · Accepted Answer · 2016-05-28 22:02:23Z

1

var n = text.length; //The size of your random string
var randomPosition = Math.floor((Math.random() * n) + 1); //Generate a  random number between 1 and the size of your string

//Separate your string in 2 strings
var text1 = text.substring(1, randomPosition); 
var text2 = text.substring(randomPosition, n); 

//Create your final string by adding the common string between your two halves
var textFinal = text1 + commonString + text2;

return textFinal;

I don't remember how exactly works .substring(), you may want to change 1 by 0 in some places.

answered May 28, 2016 at 22:02

user5455540

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Comments

Andrew Eisenberg · Accepted Answer · 2016-05-28 21:58:32Z

1

A rough sketch of the algorithm is this:

create random string of length size - <FIXED_STRING>.length
append <FIXED_STRING> to the end of generated string

Done.

A corner case is if size < <FIXED_STRING>.length, here you would need to provide some more discussion on what should happen.

answered May 28, 2016 at 21:58

Andrew Eisenberg

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1 Comment

Dazzler Over a year ago

Thank you for the answer :) It gave me an idea I could try it on my own as well :)

guest271314 · Accepted Answer · 2016-05-28 22:17:03Z

1

You can use String.prototype.slice() to select 0-n characters from possible to insert into random index within string returned from randomTextArrayGeneration. If 0 is passed to randomTextArrayGeneration the selected string from possible will be set as result

var randomTextArrayGeneration = function(size, from, to) {
      var text = "";
      var possible = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
      for (var i = 0; i < size; i++) {
        text += possible.charAt(Math.floor(Math.random() * possible.length))
      };
      var len = Math.floor(Math.random() * text.length - 3);
      var res = text.slice(0, len) + possible.slice(from, to).toLowerCase() + text.slice(len);
      return res
}

edited May 28, 2016 at 22:17

answered May 28, 2016 at 22:08

guest271314

1

1 Comment

Dazzler Over a year ago

Thank you for the answer :)

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