Switch character position using javascript/jQuery

Question

I have a string for example:

var string = 'This is a test sentence. Switch the characters. i .';

I want to switch position of every occurrence of the letter 'i' with the character following it except if the following character is a 't' or a non character like 'spaces' or 'line breaks'. So the result output should be some thing like:

Thsi si a test sentence. Switch the characters. i . // switches 's' but not 't' and 'space'

Is such a task possible with regular expressions? The characters I am working with are unicode characters. 'i' is just for an example. Which means matching all characters isn't a good idea. May be a not expression? I have tried some looping replaces but these aren't elegant (or efficient). Any ideas?

Jerry · Accepted Answer · 2014-01-28 13:21:17Z

4

You can use a replace with a regex of that form:

var string = 'This is a test sentence. Switch the characters. i .';
var result = string.replace(/(i)(?![t\s])(.)/g, "$2$1");

jsfiddle demo

(i) matches and captures i into the variable $1.

(?![t\s]) prevents the matching of t and space.

(.) matches and captures any other character into the variable $2.

answered Jan 28, 2014 at 13:21

Jerry

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3 Comments

Dan Over a year ago

Elegant one liner solution. Works great.

pewpewlasers Over a year ago

This is great. I am sorry but I am weak with regex. How does this change if let's say we want to check the preceding character?

Jerry Over a year ago

@pewpewlasers You could perhaps use another capture group (JS unfortunately doesn't support lookbehinds). Let's say another condition to what we have is that when i is preceded by a space, no switching should be made. You could do: string.replace(/(\S|^)(i)(?![t\s])(.)/g, "$1$3$2"); The \S will match a non-space, ^ will match the beginning of a line if the string is like var string = 'island';. The regex is going to match either \S or (indicated by |) ^.

Sujith PS · Accepted Answer · 2014-01-28 14:20:27Z

1

You can use regex:/(i)([^t\W])/gi

Code :

var string = 'This is a test sentence. Switch the characters. i .';
string.replace(/(i)([^t\W])/gi,"$2$1");

DEMO

Explanation :

enter image description here

answered Jan 28, 2014 at 14:20

Sujith PS

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