CODEWITHSUNDEEP
javascriptstring
Scheintod
Scheintod

Reputation: 8115

Javascript swap characters in string

Let's say I have a string like "abcabcabc" and I want the positions of 'a's and 'b's swapped so that I end up with "bacbacbac". What is the most elegant solution for this? (For the sake of this question I hereby define 'elegant' as fast and readable.)

I came up with

"abcabcabc".replace( /[ab]/g, function( c ){ return { 'a': 'b', 'b': 'a' }[ c ] } )

Which I neither regard fast nor readable. But now I wonder if there is a better way of doing it?

EDIT: The characters can be at any position. So the answer should hold for "xyza123buvwa456" (would be then "xyzb123auvwb456", too.

EDIT2: "swap" seems to be the wrong word. Replace all of a with b and all of b with a while both are single characters.

I throw in a couple of other ones:

"abcabcabc".replace( 'a', '_' ).replace( 'b','a' ).replace( '_', 'b' )

"abcabcabc".replace( /[ab]/g, function( c ){ return "ba".charAt( c.charCodeAt()-'a'.charCodeAt() ); } )

"abcabcabc".replace( /[ab]/g, function( c ){ return "ab".charAt( "ba".indexOf( c ) ) } )

I ended up using a modified version of Mark C.'s Answer:

"abcabcabc".replace( /[ab]/g, c => c == 'a' ? 'b' : 'a' )

Upvotes: 8

Views: 20832

Answers (5)

User
User

Reputation: 79

I use this method when I need to swap long list of characters\words\strings!

The method also prevents strings already replaced to be replaced again, Example:

String = "AAABBBCCC BBB"

Replace "AAABBBCCC" with "BBB", then, "BBB" with "DDD"

Final String = "BBB DDD"

Note that, only "BBB" from the original string is replaced to "DDD"! The "BBB" replaced from "AAABBBCCC" is not re-replaced to "DDD"!

Upvotes: 1

CRice
CRice

Reputation: 32176

You can swap them (if they're always adjacent) by using a split/join combo:

console.log("abcabcabc".split("ab").join("ba"))

And in keeping with the split/join method, here's a way to swap them as individual characters (although it becomes significantly less readable):

console.log("aabbccaabbcc".split("a").map(s => s.split("b").join("a")).join("b"));

Upvotes: 4

Mark C.
Mark C.

Reputation: 6450

Try this :

str.replace(/[ab]/g, function($1) { return $1 === 'a' ? 'b' : 'a' })

example: 

console.log("abcabcabc".replace(/[ab]/g, function($1) { return $1 === 'a' ? 'b' : 'a' }))

Upvotes: 14

Ele
Ele

Reputation: 33726

Use a direct replace using Regex:

var result = "abcabcabc".replace( /ab/g, "ba");
console.log(result);

Upvotes: 0

Leon Plata
Leon Plata

Reputation: 622

replace function accepts a string as the second parameter.

"abcabcabc".replace( /ab/g, "ba")

Upvotes: 1

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