Javascript:Regular Expression related functions on string

Search:

The simplest regular expression related string method is search(), which

takes a regular expression argument and returns the index of the character at

which the first matching substring begins. If no substring matching the

pattern is found, –1 is returned.

Code:

var str = "The Powerpacked Javascript:The Javascript Regular Expression are Powerfull!"

console.log(str.search(/powerf.*/i))

output:

65

split():

The second method provided by string is also fairly simple. The split()

method splits (for lack of a better word) a string into substrings and

returns them in an array. It accepts a string or regular expression

argument containing the delimiter at which the string will be broken.

Code:

var delimitedString="9 |27 |36 |45 |54 |63 |72 |81 |90"

//use character classes while splitting

var pattern = /[ \|]+/

//var pattern = /[|]+/

//do not use character group while splitting

//var pattern = /( \|)+/

var arr = delimitedString.split(pattern)

console.log(arr)

Output:

[

'9', '27', '36',

'45', '54', '63',

'72', '81', '90'

]

Replace:

The replace() method returns the string that results when you replace text

matching the method’s first argument (a regular expression) with the text of

the second argument (a string). If the global (g) flag is not set in the

regular expression declaration, this method replaces only the first occurrence

of the pattern.

Code:

var landline = "912367233427"

var pattern=/(\d{2})(\d{4})(\d{6})/

//hypeneted

var formattedLandline = landline.replace(pattern,"$1-$2-$3")

console.log(formattedLandline)

output:

91-2367-233427

match( )

method takes a regular expression as an argument and returns an array

containing the results of the match. If the given regular expression has

the global (g) flag, the array returned contains the results of each substring

matched.if match() does not find a match, it returns null.

Code:

var delimitedString="9 |27 |36 |45 |54 |63 |72 |81 |90"

var pattern = /\d{1,}/g

var result = delimitedString.match(pattern)

console.log(result)

Output:

[

'9', '27', '36',

'45', '54', '63',

'72', '81', '90'

]

or

Code:

var delimitedString="9 |27 |36 |45 |54 |63 |72 |81 |90"

var pattern = /(\d{1,})/g

var result = delimitedString.match(pattern)

console.log(result)

Output:

[

'9', '27', '36',

'45', '54', '63',

'72', '81', '90'

]