Javascript Course


The strip_tags(), and stripslashes() functions are generally known and used in PHP. These functions are useful when working with strings that contains HTML code, but JavaScript doesn't have such functions.
Here's these functions for JavaScript.

strip_tags

strip_tags(string, allow) - returns a string with HTML and PHP tags stripped from a given string. HTML comments are also stripped.
The allow parameter is optional, and represents a string with allowable tags, which should not be stripped (a string like: '<b><i><u>').
Code:
function strip_tags(str, allow){
 // making sure the allow arg is a string containing only tags in lowercase (<a><b><c>)
 allow = (((allow || '') + '').toLowerCase().match(/<[a-z][a-z0-9]*>/g) || []).join('');

 var tags = /<\/?([a-z][a-z0-9]*)\b[^>]*>/gi;
 var commentsAndPhpTags = /<!--[\s\S]*?-->|<\?(?:php)?[\s\S]*?\?>/gi;
 return str.replace(commentsAndPhpTags, '').replace(tags, function ($0, $1) {
 return allow.indexOf('<' + $1.toLowerCase() + '>') > -1 ? $0 :'';
 });
}

Example:
<div id='sresult'>#sresult</div>

<script>
function strip_tags(str, allow){
 // making sure the allow arg is a string containing only tags in lowercase (<a><b><c>)
 allow = (((allow || '') + '').toLowerCase().match(/<[a-z][a-z0-9]*>/g) || []).join('');

 var tags = /<\/?([a-z][a-z0-9]*)\b[^>]*>/gi;
 var commentsAndPhpTags = /<!--[\s\S]*?-->|<\?(?:php)?[\s\S]*?\?>/gi;
 return str.replace(commentsAndPhpTags, '').replace(tags, function ($0, $1) {
 return allow.indexOf('<' + $1.toLowerCase() + '>') > -1 ? $0 :'';
 });
}

var str = '<p>Test paragraph.</p><!-- Comment --> <a href="https://coursesweb.net/">CoursesWeb.net</a>.<br>New line: <b>Bold</b>, and <u>Underline</u>. An opening Span tag: <span>*';

var str1 = strip_tags(str); // removes all tags
var str2 = strip_tags(str, '<b><u>'); // keeps <b> and <u> tags

// adds str1 and str2 in webpage
document.getElementById('sresult').innerHTML = 'str1: '+ str1+ '<br/>str2: '+ str2;
</script>
Result:
str1: Test paragraph. CoursesWeb.net.New line: Bold, and Underline. An opening Span tag: *
str2: Test paragraph. CoursesWeb.net.New line: Bold, and Underline. An opening Span tag: *

stripslashes

stripslashes() - un-quotes a quoted string. Returns a string with backslashes stripped off. (\', and \' become ' and ') Double backslashes (\\) are made into a single backslash (\).
Code:
function stripslashes(str) {
 return str.replace(/\\'/g,'\'').replace(/\"/g,'"').replace(/\\\\/g,'\\').replace(/\\0/g,'\0');
}

Example:
// stripslashes
function stripslashes(str) {
 return str.replace(/\\'/g,'\'').replace(/\"/g,'"').replace(/\\\\/g,'\\').replace(/\\0/g,'\0');
}

var str = 'String with \"backslashes\", \\ coursesweb.net/';
str = stripslashes(str);
str = stripslashes(str);

document.write(str); // String with 'backslashes', \ coursesweb.net/

Daily Test with Code Example

HTML
CSS
JavaScript
PHP-MySQL
Which HTML5 tag is indicated to be used as container for menu with navigation links in Web site?
<section> <nav> <article>
<nav><ul>
 <li><a href="http://coursesweb.net/css/" title="CSS Course">CSS Course</a></li>
 <li><a href="http://www.marplo.net/jocuri/" title="Flash Games">Flash Games</a></li>
</ul></nav>
Which CSS property shifts an item horizontally to the left or right of where it was?
text-align clear float
.some_class {
  width: 30%;
  float: left;
}
Click on the Math object method which returns x, rounded downwards to the nearest integer.
Math.ceil(x) Math.abs(x) Math.floor(x)
var num = 12.34567;
num = Math.floor(num);
alert(num);       // 12
Indicate the PHP function which returns the number of characters in string.
mb_strlen() count() stristr()
$str = "string with utf-8 chars åèö";
$nrchr = mb_strlen($str);
echo $nrchr;        // 30
JavaScript strip_tags and stripslashes

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