How to do case-insensitive matching using JavaScript RegExp?-HTML Tutorial-php.cn

How to do case-insensitive matching using JavaScript RegExp?

王林

Release： 2023-09-07 17:09:02

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如何使用JavaScript RegExp进行不区分大小写的匹配？

In this tutorial, we will learn how to use JavaScript RegExp to perform case-insensitive matching.

Regular expressions can be declared in two ways -

Use regular expression literals, starting and ending with a slash, and The pattern is placed between the two.
Call the RegExp object constructor, which takes Parameters used to create regular expressions.

Users can use the following syntax to create regular expressions.

grammar

//Using a regular expression literal
const regex = /tutorial/i
//Using RegExp constructor
const regex2 = new RegExp('tutorial', 'i')

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In the above syntax, the regular expression is created to match the word "tutorial", the modifier "i" means that it can match any substring with these characters, regardless of their case ("TuToRial", "Tutorial" ,wait).

Use string match() method

The match() method is part of the String object in JavaScript. It is used to match strings with RegExp or regular expressions.

Users can use the match() method with JavaScript RegExp according to the following syntax to perform case-insensitive matching.

grammar

text.match(regex)

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In the above syntax, "text" is a string that needs to be checked using a regular expression. "regex" is a regular expression pattern.

parameter

regex - It is a regular expression or a string that will be converted to a regular expression.

Return type

Returns an array of all matches, or null if no match is found.

Example

In the example given below, we use the match() method to perform case-insensitive matching. We are checking the match method result when the button is clicked and outputting it.

<html>
<body>
   <h4>Performming Case Insensitive Matching with RegExp using <i>
   match() </i> method</h4>
   <button onclick="check()">Check</button>
   <p>Original Text: Welcome to Tutorialspoint</p>
   <p>Text To Match: tutorial </p>
   <p id="output"></p>
   <script>
      const text='Welcome to Tutorialspoint'
      const regex=/tutorial/i
      function check(){
         //Using the match method
         let result=text.match(regex)
         document.getElementById('output').innerHTML='Mached Text: '+result
      }
   </script>
</body>
</html>

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The above output shows that the match() method returns the matching substring "Tutorial".

Use the string search() method

The search() method is part of the String object in JavaScript. It is used to search for a substring of a string based on a RegExp or regular expression.

Users can use the search() method with JavaScript RegExp according to the following syntax to perform case-insensitive matching.

grammar

text.search(regex)

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In the above syntax, "text" is a string and "regex" is a regular expression pattern.

parameter

regex - It is a regular expression or a string that will be converted to a regular expression.

Return type

Returns the position of the first match, or -1 if no match is found.

Example

In the example given below, we have used the search() method and on click of the button we are checking the result of the search() method and outputting it.

<html>
<body>
   <h4>Performming Case Insensitive Matching with RegExp using <i>
   search() </i> method.</h4>
   <p>Text: Welcome to Tutorialspoint</p>
   <p>Text to Match: tutorial</p>
   <button onclick="check()">Check</button>
   <p id="output"></p>
   <p><b>Note:</b>The search() method returns the position of first
   match</p>
   <script>
      const text='Welcome to Tutorialspoint'
      const regex=/tutorial/i
      function check(){
         //Using search method
         let result=text.search(regex)
         document.getElementById('output').innerHTML='Result: '+result
      }
   </script>
</body
</html>

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In the above output, the user can see that the search() method returns the starting position of the substring "Tutorial".

Use RegExp test() method

The test() method is part of the RegExp object in JavaScript. It is used to test strings based on RegExp or regular expressions.

Users can use the test() method with JavaScript RegExp according to the following syntax to perform case-insensitive matching.

grammar

regex.test(text)

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In the above syntax, "text" is a string that needs to be checked using a regular expression. "regex" is a regular expression pattern.

parameter

Text/String - This is the text or string to be tested.

Return type

Returns false if no match is found, otherwise returns true.

Example

In the example given below, we have used the test() method.

<html>
<body>
   <p>Performming Case Insensitive Matching with JavaScript RegExp using <i>
   test() </i> method</p>
   <p>Text: Welcome to Tutorialspoint</p>
   <p>Text to Match: tutorial</p>
   <button onclick="check()">Check</button>
   <p id="output"></p>
   <p><b>Note:</b> The test() method returns true if there is a match, else
   returns false.</p>
   <script>
      const text = 'Welcome to Tutorialspoint'
      const regex = /tutorial/i
      function check() {
         //Using the test method
         let result = regex.test(text)
         document.getElementById('output').innerHTML = 'Result: ' + result
      }
   </script>
</body>
</html>

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In the above output, the user can see that the test() method returns true because the "Tutorial" substring is present in the text.

Use RegExp exec() method

The exec() method is part of the RegExp object in JavaScript. It is used to match strings with RegExp or regular expressions.

Users can use the exec() method with JavaScript RegExp according to the following syntax to perform case-insensitive matching.

grammar

regex.exec(text)

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In the above syntax, "text" is a string and "regex" is a regular expression pattern.

parameter

Text/string - The text or string to be matched.

Return type

Returns an array of all matches, or null if no match is found.

Example

In the example given below, we have used the exec() method.

<html>
<body>
   <p>Performming Case Insensitive Matching with JavaScript RegExp using
   <i> exec() </i> method</p>
   <button onclick="check()">Check</button>
   <p>Text: Welcome to Tutorialspoint</p>
   <p id="output"></p>
   <script>
      const text='Welcome to Tutorialspoint'
      const regex=/tutorial/i
      function check(){
         //Using the exec method
         let result=regex.exec(text)
         document.getElementById('output').innerHTML='Result: '+result
      }
   </script>
</body>
</html>

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The above output shows that the exec() method returns the matching substring "Tutorial".

In this tutorial, we discussed four ways to use RegExp to perform case-insensitive matching. The first two methods are the string match() and search() methods. The other two methods are the RegExp test() and exec() methods.

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