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Home  >  Article  >  Web Front-end  >  How to convert special characters to HTML in Javascript?

How to convert special characters to HTML in Javascript?

PHPz
PHPzforward
2023-09-03 17:41:02675browse

How to convert special characters to HTML in Javascript?

We can use the replace() method to convert special characters to HTML in JavaScript. This method can also be applied to maps. There are many other methods for this task. We will discuss these methods in detail in this article. We first discuss the need to convert special characters to HTML, and then we will discuss methods of special character conversion. First let's talk about some concepts of characters, and then we'll bring up our next topic.

Need to convert special characters to HTML

We've seen our developers write thousands of lines of code to accomplish specific tasks. Now, let's say we need to use less than () symbol in a web page or a mobile application using HTML as scripting language. Well, this becomes a problem because the less than () symbol has a special meaning for the scripting language HTML.

These flags are typically used to initialize tags in HTML. Likewise, using the special character in an attribute value may cause the attribute to be misinterpreted. So, to overcome this problem, we have special codes for every special character present while using HTML. To insert special characters in HTML, start with an ampersand (&), then a pound sign (#), then the code number, and end with a semicolon (;). For example, the (copyright) symbol can be represented by ©.

Method to convert special characters to HTML

There are several ways to convert special characters to HTML. Some of the most common methods are listed below.

Use String.prototype.replace() method

The String.prototype.replace() method in JavaScript is used to replace special characters with another value in a string.

String.prototype.replace() has two parameters, the first parameter is the value to be replaced, and the second parameter is the value to be replaced in the string.

This method returns a new string with all search values ​​replaced with the desired values ​​in the string. However, the String.prototype.replace() method does not change the value of an existing string. Let's look at an example.

Example

<html>
<body>
   <p id="print"></p>
   <script>
      var string = "This is a <string>";
      string = string.replace(/</g, "<");
      document.getElementById("print").innerHTML = string;
   </script>
</body>
</html>

Use String.prototype.replace() with Map

String.prototype.replace() method can also be used with Map in JavaScript. Here String.prototype.replace() also has two parameters. The first parameter is the regular expression pattern to be replaced, and the second parameter is the matching substring.

Example

p>

Let's look at an example of using map with string.prototype.replace() -

<html>
<body>
   <p id="print"></p>
   <script>
      const specialCharsMap = new Map([
         ["<", "<"],
         [">", ">"],
         ["&", "&"],
      ]);
      function replaceSpecialChars(string) {
         for (const [key, value] of specialCharsMap) {
            string = string.replace(new RegExp(key, "g"), value);
         }
         return string;
      }
      document.getElementById("print").innerHTML =
      replaceSpecialChars("This is a <string>");
   </script>
</body>
</html>

Use encodeURIComponent() function

We can also use the encodeURIComponent() function in javascript to replace special characters with another value in the string. We typically use this function to encode Uniform Resource Identifier (URI) components. It replaces specific characters in a string with their escaped counterparts to ensure the string is safe for use in URIs.

Now, to use this function, we just need to pass a string (str) as a parameter in the function. This method also returns a new string with all search values ​​replaced with the desired values ​​in the string. Like the String.prototype.replace() method, this function does not change the value of an existing string. Let's look at an example.

Example

<html>
<body>
   <p id="print"></p>
   <script>
      var str = "Hello, < world > !";
      var newStr = encodeURIComponent(str);
      document.getElementById("print").innerHTML = newStr;
   </script>
</body>
</html>

You should remember when using this function that it only works with a few special characters. To handle some other special characters, you must use multiple methods or additional logic to handle them.

Use the escape() function

The escape() function, like the encodeURIComponent() function, is used to encode a string so that it does not cause any problems with the URL of the website. To use this function, we simply pass a string (str) as a parameter into the function. This method also returns a new string with all search values ​​replaced with the desired values ​​in the string.

Example

This is an example of the escape() function -

<html> 
<body>
   <p id="print"></p>
   <script>
      var str = "Hello, <world>!";
      var newStr = escape(str);
      document.getElementById("print").innerHTML = newStr;
   </script>
</body>
</html>

in conclusion

In this blog, we first introduce special characters, the need to convert them and the various methods you can use to do so. Some of the methods discussed here are using String.prototype.replace(), using String.prototype.replace() with Map, using encodeURIComponent() function and escape() function. Other methods that can be used are innerHTML, replace, document.createElement, etc.

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JavaScript 正则表达式 html String 标识符 字符串 map prototype innerHTML
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