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Home  >  Article  >  Web Front-end  >  How to trim the beginning or end of a string in JavaScript?

How to trim the beginning or end of a string in JavaScript?

WBOY
WBOYforward
2023-08-29 13:57:021061browse

如何在 JavaScript 中修剪字符串的开头或结尾？

When processing data, it is necessary to remove unnecessary spaces from the string. Therefore, we need to trim the string at the beginning or end.

If we keep unnecessary spaces in the data, it may cause some problems. For example, if we don't trim spaces when storing passwords, the passwords may not match when the user tries to log in to the application at other times.

In this tutorial, we will learn to trim the beginning or end of a string in JavaScript.

Use trimRight() method to trim the end of the string

trimRight() method allows us to remove spaces at the end of a string.

grammar

Users can use the trimRight() method to trim the string from the end according to the following syntax. 

let result = string1.trimRight();

In the above syntax, string1 is a string that is trimmed from the end, and we store the final string in the result variable.

Example 1

In the example below, we create two strings that contain spaces at the beginning and end of the string. After that, we use trimRight() method to remove the spaces at the end of the string. 

<html>
<body>
   <h2>Using the <i> trimRight() </i> method to trim the string from the end in JavaScript.</h2>
   <div id = "output"></div>
   <br>
</body>
<script>
   let output = document.getElementById("output");
   let string1 = " Trim from right! ";
   let string2 = "Trim from the end ! ";
   string1 = string1.trimRight();
   string2 = string2.trimRight();
   output.innerHTML += "The final string1 is *" + string1 + "*. <br>";
   output.innerHTML += "The final string2 is *" + string2 + "*. <br>";
</script>
</html>

Use trimLeft() method to trim the beginning of the string

We can use the trimLeft() method to trim the string from the beginning.

grammar

Users can use the trimLeft() method according to the following syntax to remove spaces at the beginning of the string. 

let pass1 = pass1.trimLeft();

In the above syntax, we use the trimLeft() method with pass1 string.

Example 2

In the example below, we have two password strings that contain spaces at the beginning. After that, we use trimLeft() method to remove the spaces at the beginning of the string.

Users can observe the output of strings without spaces at the beginning. 

<html>
<body>
   <h2>Using the <i> trimLeft() </i> method to trim the string from the start in JavaScript.</h2>
   <div id = "output"></div>
   <br>
</body>
<script>
   let output = document.getElementById("output");
   let pass1 = " abcd@123 "
   let pass2 = " pok.=-E3434";
   pass1 = pass1.trimLeft();
   pass2 = pass2.trimLeft();
   output.innerHTML += "The final string1 is *" + pass1 + "*. <br>";
   output.innerHTML += "The final string2 is *" + pass2 + "*. <br>";
</script>
</html>

Use the trim() method to trim the left and right ends of the string together

The trim() method of the string library allows us to remove all spaces at the beginning and end of the string at once, instead of using the trimLeft() and trimRight() methods individually.

grammar

Users can use the trim() method to trim the beginning or end of the string according to the following syntax. 

str = str.trim();

In the above syntax, str is a string containing spaces at the beginning and end of the string.

Example 3

In the example below, we allow the user to enter a string with spaces in the prompt box. After that, we use trim() method to remove the spaces and display the final result in the output. 

<html>
<body>
   <h2>Using the <i> trim </i> method to trim the string from the start in JavaScript.</h2>
   <div id = "output"></div>
   <br>
</body>
<script>
   let output = document.getElementById("output");
   let str = prompt("Enter the string with white spaces at start and end.", " abcd efg ")
   str = str.trim(); 
   output.innerHTML += "The final string1 is *" + str + "*. <br>";
</script>
</html>

We learned to use various methods to trim strings from beginning to end. The trimLeft() method is used to trim the string from the left side, and the trimRight() method is used to trim the string from the right side. Additionally, we use the trim() method to trim leading and trailing spaces.

In addition, users can also use the trimStart() and trimEnd() methods to trim the string from both ends.

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