Jquery update div content. Refresh web page content without reloading using JavaScript

Regular expressions are one of the most powerful data manipulation tools in JavaScript. In addition, this is the most convenient way to process data in cases where it is impossible to specify an exact search pattern. The simplest example is to highlight all email addresses and phone numbers in the text. Obviously, a simple search for a substring will not work, because We do not know in advance which addresses and telephone numbers will appear in the text.

Regular expressions do not operate on exact values, but on patterns. A pattern is written using the regular expression language, and we will now get acquainted with its basics.

So, any regular expression consists of a separator, a template body and modifiers (sometimes they are also called switches).

/pattern/switch

Here "/" is the separator, "pattern" is the body of the pattern, and "switch" is the modifiers.

There are only two ways to use regular expressions in JavaScript: using the methods of the RegExp object or using the methods of the String object.

An instance of a RegExp object can be created in two ways - explicit and indirect:

// explicit method var re = new RegExp("pattern", "switch"); // indirect (alternative) method var re = /pattern/switch;

Please note that with the indirect method, the pattern is specified WITHOUT quotes.

Any regular expression consists of regular characters, special characters and repetition quantifiers. Common characters include letters, numbers, and symbols, but national characters and Unicode characters can be used as characters. Attention! "Space" is also considered significant in regular expressions, so be very careful when adding spaces to your expression. Better yet, use a special metacharacter (see the \s symbol in the table below).

Special characters (or metacharacters) are the basis of regular expressions, because It is the special characters that determine the search order and indicate to the expression interpreter additional conditions and restrictions. The table shows the main special characters and gives a brief description of them.

There are a lot of special characters and with their help you can describe almost any phrase or search phrase.

The second component of the pattern is quantifiers. This is a subset of special characters that sets the condition for the repetition of characters or their groups. The quantifier is written to the right of the expression and extends to the nearest character or group. For example:

(pattern_1)|(pattern_2)(quont)

Here the quantifier "quont" refers only to "pattern_2".

The table shows all the main quantifiers:

So, we have become familiar with the basics of the regular expression language and now we will try out our new knowledge in practice. Here is an example of using the test() method

var sample = "Oranges are made into orange juice"; var re = /orange*/; var result = re.test(sample) ? "" " : "" Not "; document.write("The string "" + sample + result + "matches the pattern " + re);

Example of using exec() method

var sample = "Oranges are made into orange juice"; var re = /orange*/; var result = re.exec(sample); document.write("Match found: "" + result + """);

And in this example we will use an alternative way to create a RegExp object:

var sample = "Oranges are made into orange juice"; var result = /orange*/.test(sample) ? "" " : "" Not "; document.write("The string "" + sample + result + "matches the sample ");

The following example is a real working script. It allows you to get rid of the bug with displaying the transparency of PNG images in Internet Explorer versions 5 and 6. We have already mentioned this script when considering layers and their use in JavaScript.

Function correctPNG() ( // check the user's browser signature string if (/MSIE (5\.5|6).+Win/.test(navigator.userAgent)) ( for(var i=0; i