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JavaScript equivalent to printf/String.Format

Learn about the methods equivalent to printf/String.Format.
Submitted by Pratishtha Saxena, on June 18, 2022

In JavaScript, printf keyword cannot be used to print as we use this in many other languages like C, etc. There is the different way to print string in JavaScript.

1) Using console.log()

One way is by using console.log(). This helps in printing it on the console. It is the most common form of printing and is used by many developers. It is as simple as printf. The string/variable that has to be printed is specified in the same way as it is specified in printf.

Syntax:

console.log("...");

Example 1:

<script>
  var a = "This is Example 1."
  
  console.log(a);
  console.log("This is a string.");
  console.log(500);
</script>

Output:

Another way is by using JavaScript String.format().

2) Using String.format() Function

When you want to customize the string, then String.format() function is used. Using this simple formatting of the string can be done on your own simultaneously.

So basically, this works such that within the string it looks for the curly brackets {}, and replaces the index/value inside it with the value specified at the right hand side of the .format keyword.

Example 2:

<script>
    String.prototype.format = function () {
        var args = arguments;
        return this.replace(/{(\d+)}/g, function (match, number) {
        return typeof args[number] != "undefined" ? args[number] : match;
        });
    };
    console.log("{0} is a country, furthermore {1} is it's capital {0}, {2}".format("India", "New Delhi"));
</script>

Output:

JavaScript Examples »

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