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Posted 20 May 2014


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String Formatting in JavaScript

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20 May 2014CPOL
String.Format creates strings from a pattern and values


Replaces each format item in a specified string with the text equivalent of a corresponding parameters value. One or more format items in a specified string with the string representation of a specified parameter value.


'string with format{0}'.format(Object arg0, Object arg1, Object argn);
  • {0}: type of string object
  • arg0: The first object to format
  • arg1: The second object to format
  • argn: The nth object to format

Using the Code

String.prototype.format = function () {
    var args = arguments;
    return this.replace(/\{\{|\}\}|\{(\d+)\}/g, function (m, n) {
        if (m == "{{") { return "{"; }
        if (m == "}}") { return "}"; }
        return args[n];


This example shows the use of the string.Format method to combine three strings with formatting options. The format string itself is the first argument to the string.Format method and it is specified as a string literal.

The "{0}", "{1}", "{2}" and "{N}" indicate where the first, second, third and Nth arguments are inserted into the string object. The parameter should be between the { } brackets.

"Hello {0}.{1}, Welcome to our new house at {2}.".format('Mr','Imdadhusen','Ahmedabad');
Hello Mr.Imdadhusen, Welcome to our new house at Ahmedabad.

More Examples

var startDate = "21 APR 2014";
var endDate = "24 APR 2014";
"Your score is {0} out of {1}".format(175,250);
"Dear {0}, Your ticket is booked for {1} days from {2} to {3}. 
Thank you for booking from {4}".format('Imdadhusen',4,startDate, endDate, '');
"World T{0} - {1}th match, Group {2}, {3} v {4}, {3} won by {5} wickets 
(with {6} balls remaining).  {4}'s next match will be on {7}.".format
(20,13,2,'India','Pakistan', 7, 9, '25 Apr 2014');
Your score is 175 out of 250 

Dear Imdadhusen, Your ticket is booked for 4 days from 21 APR 2014 to 24 APR 2014. 
Thank you for booking from

World T20 - 13th match, Group 2, India v Pakistan, India won by 7 wickets 
(with 9 balls remaining). Pakistan's next match will be on 25 Apr 2014.

Points of Interest

Using the above string utility you can pass n number of parameters with repetitive parameter to generate complete string.

Please feel free to ask me if you would require any help for the same.

Your valuable feedback, comments, suggestions are highly appreciated.


This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)


About the Author

Sunasara Imdadhusen
Technical Lead Infostretch Ahmedabad-Gujarat
India India
Aspiring for a challenging carrier wherein I can learn, grow, expand and share my existing knowledge in meaningful and coherent way.

sunaSaRa Imdadhusen


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Comments and Discussions

Questionsimple and easy to learn Pin
Jcmorin21-May-14 6:33
MemberJcmorin21-May-14 6:33 
from any .NET programmer this is super easy to learn and use.

Good job!
AnswerRe: simple and easy to learn Pin
Sunasara Imdadhusen21-May-14 18:29
professionalSunasara Imdadhusen21-May-14 18:29 

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