How to return all matching strings against a RegEx in JavaScript?

Javascript Web Development Front End Technology

In this article, we will explore the essentials of a regular expression (RegEx) and how to compare other strings with this regex in JavaScript. We will learn how to identify a similar string with that of a regex and then subsequently return them. We can use the string.search() method to match the regular expression in a given string.

Syntax

let index = string.search(expression)

Parameters

string − This is the string that will be searched in comparison with the expression.
expression − This is the regular expression that will be used for checking with the original string.

Example 1

In the below example, we are going to compare a string with a substring/regular expression that is rendered in the function. This method will only return the elements that match the expression, else the string will not be returned.

# index.html

<!DOCTYPE html>
<html>
<head>
   <title>
      Comparing Strings
   </title>
</head>
<body>
   <h2 style="color:green">
      Welcome To Tutorials Point
   </h2>
</body>
   <script>
      // Taking a String input.
      var string = "Start Learning new technologies now.";

      // Defining a regular expression
      var regexp1 = /Lea/;
      var regexp2 = /rn/;
      var regexp3 = /abc/;
      console.log("Matched at:"+string.search(regexp1));

      // Expected Output: 6
      console.log("Matched at:"+string.search(regexp2));

      // Expected Output: 9
      console.log("Matched at:"+string.search(regexp3));

      // Expected Output: -1
   </script>
</html>

Output

Example 2

# index.html

<!DOCTYPE html>
<html>
<head>
   <title>
      Comparing Strings
   </title>
</head>
<body>
   <h2 style="color:green">
      Welcome To Tutorials Point
   </h2>
</body>
   <script>
      // Taking input an array of strings.
      let input = [
         "Tutorials Point has 40 million readers every month",
         "Start your journey with Tutorials Point",
         "It started in 2006",
         "Start Learning",
         "Tutorials Point started in 2006"
      ];
      let i;
      // Defining the regular expression
      let regexp = /Tutorials/;
      let result = [];
      for (i = 0; i < input.length; i++) {
         if (input[i].search(regexp) != -1) {
            result.push(input[i])
         }
      }
      console.log("Resultant array is:"+result)
   </script>
</html>