Replacing some characters in string JavaScript

Question

I need to replace multiple characters in a string. I have a line - "123AB"

And I need to replace the A at %D1, and B at %D2.

How do I do this? Can it be done with .replace, if so, how?

Yes, it can be done with String.replace. Read the API docs. developer.mozilla.org/en-US/docs/JavaScript/Reference/… — Matt Ball
– Matt Ball, Commented Dec 4, 2012 at 17:44

Ruan Mendes · Accepted Answer · 2012-12-04 17:48:00Z

5

String.replace is very simple

"ABCDEFA".replace(/A/g, "a") // outputs "aBCDEFa"
"ABCDEFB".replace(/B/g, "b") // outputs "AbCDEFb"

So you could use

"123AB".replace(/A/g, "%D1").replace(/B/g, "%D2");

However, you can do it in one pass by passing a replacement function instead of a string to replace

"123AB".replace(/A|B/g, function(match) {
     var repacements = {A: '%D1', B: '%D2'};
     return replacements[match];
})

answered Dec 4, 2012 at 17:48

Ruan Mendes

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Comments

Esailija · Accepted Answer · 2012-12-04 17:47:59Z

2

It's pretty straightforward, first argument is what you want to replace and second argument is what you want to replace it with:

var str = "123AB";
str = str.replace( "A", "%D1" ).replace( "B", "%D2");
//str is now "123%D1%D2"

answered Dec 4, 2012 at 17:47

Esailija

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4 Comments

Esailija Over a year ago

yes it does, it replaces the a and the b as op requested :I

Ruan Mendes Over a year ago

@Esailija It only works for the input the OP requested, not if there are multiple As or Bs. "123ABABAB".replace( "A", "%D1" ).replace( "B", "%D2"); outputs "123%D1%D2ABAB" You need the regular expression to make it a global replace

Esailija Over a year ago

@JuanMendes yes I know that, but the op asked for a simple replace that works for his input :-p

Ruan Mendes Over a year ago

@Esailija That is a sample string, you can't assume that is the only possible input, can you?

Jude Fisher · Accepted Answer · 2012-12-04 18:04:38Z

0

This should work .. str.replace("A",D1)

edited Dec 4, 2012 at 18:04

Jude Fisher

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answered Dec 4, 2012 at 17:47

Arun

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Comments

thiagoh · Accepted Answer · 2012-12-04 17:49:13Z

-1

this replaces all the occurencies

var rep = function (s, search, replacement) { 
   while(s.indexOf(search) >= 0) 
       s = s.replace(search, replacement); 
   return s;
}
var s = rep("123AB", "A", "%D1");

answered Dec 4, 2012 at 17:49

thiagoh

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6 Comments

Ruan Mendes Over a year ago

Yes, it works, but you're duplicating work that replace can do for you

Esailija Over a year ago

If global replace was necessary, you could have just done global replace ... s.replace( /A/g, "%D1")

Ruan Mendes Over a year ago

@IlyaKharlamov This is the worst answer out of all the available ones

thiagoh Over a year ago

but you're using regular expressions.. they are slower than mine verification.. bad for you.. =\

Esailija Over a year ago

You do realize that this is O(n²) where as regex will be O(n)? even if you didn't realize that, regex is 50 times faster here jsperf.com/replace-vs-on2

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