JavaScript: Escapes special characters for use in HTML

JavaScript String: Exercise-31 with Solution

Escape HTML Characters

Write a JavaScript function to escape special characters (&, <, >, ', ") for use in HTML.

Test Data:
console.log(escape_html('PHP & MySQL'));
"PHP &amp; MySQL"
console.log(escape_html('3 > 2'));
"3 &gt; 2"

Sample Solution:

JavaScript Code:

function escape_html(str) {
  
 if ((str===null) || (str===''))
       return false;
 else
   str = str.toString();
  
  var map = {
    '&': '&',
	'<': '<',
	'>': '>',
	'"': '"',
	"'": '''
  };

  return str.replace(/[&<>"']/g, function(m) { return map[m]; });
}
console.log(escape_html('PHP & MySQL'));
console.log(escape_html('3 > 2'));

Output:

PHP & MySQL 
3 > 2

Explanation:

In the exercise above,

• The function "escape_html()" is defined to escape HTML special characters in a given string.
• It checks if the input string is null or empty. If it is, the function returns false.
• If the input string is not null or empty, it converts it to a string.
• The function defines a map object that contains HTML special characters as keys and their corresponding HTML entities as values.
• It uses a regular expression to replace occurrences of HTML special characters in the string with their corresponding HTML entities using the "replace()" method.
• Finally, the function returns the modified string with HTML special characters escaped.

Flowchart:

Live Demo:

See the Pen JavaScript Escapes special characters for use in HTML - string-ex-31 by w3resource (@w3resource) on CodePen.

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