Replace array values with new defined values in Javascript

Question

//Get message from textarea
var msg = $('#mytextarea').val();

//Convert string to array of letters
// eg. cata = ['c','a','t','a']
var msgLettersAsArray = msg.split('');

What I need to do now is replace the single letters,something like this

c = b;
a = e;
t = c;
a = e;

//array neeeds to be converted from this:
var array = ['c','a','t','a'];

// to this:
var array = ['b','e','c','e'];

Is there any way to achieve this? All I need to do is replace the letters that are already in the array with letters of my choice

Could you just replace the letters bevor splitting the String? msg.replace(/c/g, 'b') — phylax
– phylax, Commented Apr 5, 2014 at 14:18
yes, but in the "real" code I need to replace all letters from a-z,0-9 using the replace method would require me to call the replace function for every single letter I need to change.Am I wrong? — user254883
– user254883, Commented Apr 5, 2014 at 14:22
it is possible with one call to replace(): var map = {c: 'b', a: 'e', t: 'c'}; msg.replace(/[a-z0-9]/g, function (i) { return map[i] || i; }) — phylax
– phylax, Commented Apr 5, 2014 at 14:29

plalx · Accepted Answer · 2014-04-05 14:45:50Z

3

It's quite simple, just define a translation map and use Array.prototype.map.

var translationMap = {
    c: 'b',
    a: 'e',
    t: 'c'
};

//returns ['b','e','c','e']
['c','a','t','a'].map(function (letter) { return translationMap[letter] || letter; });

EDIT: It seems you actually just wanted to replace letters in the string, in this case @phylax answer would be correct. There is no need to use arrays for a simple string replacement.

edited Apr 5, 2014 at 14:45

answered Apr 5, 2014 at 14:21

plalx

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2 Comments

Bergi Over a year ago

Please consider the case that letter is not in the translationMap before I give you an upvote :-)

Filippo oretti Over a year ago

@Bergi OP has fixed replacemtn map

Bergi · Accepted Answer · 2014-04-05 14:20:24Z

1

function replaceChars(str, map) {
    var i, reg = "";
    for (i in map)
        reg += i;
    return str.replace(
        new RegExp("["+reg.replace(/(\]|-|\\)/,"\\$1")+"]",'g'),
        function(char) { return map[char]; }
    );
}

//Get message from textarea
var msg = $('#mytextarea').val(); // "cata"

replaceChars(msg, {c:'b', a:'e', t:'c', a:'e'}); // "bece"

answered Apr 5, 2014 at 14:20

Bergi

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2 Comments

plalx Over a year ago

Did he want a string or an array? I am confused. Anyway at worst it's just a question of playing with split and join ;)

Bergi Over a year ago

@plalx: The .map() solution was too trivial and there was a String.prototype.replaceChars function in my personal helper lib so I just posted it :-)

phylax · Accepted Answer · 2014-04-05 14:37:41Z

0

Just making an answer out of my comment:

Like OP said, its ok to be done without the split(). And its possible to do with only one call to String.replace():

var map = {
  c: 'b',
  a: 'e',
  t: 'c'
};

msg.replace(/[a-z0-9]/g, function (i) { return map[i] || i; })

The RegExp can possibly made event simpler:

msg.replace(/./g, function (i) { return map[i] || i; })

answered Apr 5, 2014 at 14:37

phylax

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2 Comments

plalx Over a year ago

That's what happens when the OP doesn't explain what he needs ;)

user254883 Over a year ago

you are completely right, you deserve the best answer anyway

p.s.w.g · Accepted Answer · 2014-04-05 14:21:00Z

0

Sure, just use a for loop:

var array = ['c','a','t','a'];
for (var i = 0; i < array.length; i++)
{
    var cur = array[i];
    if (cur == 'c') {
        array[i] = 'b';
    } else if (cur == 'a') {
        array[i] = 't';
    } else if (cur == 't') {
        array[i] = 'c';
    }
}

But using an object to store these mappings can make your code even more compact:

var array = ['c','a','t','a'];
var transform = { 'c': 'b', 'a': 'e', 't': 'c' };
for (var i = 0; i < array.length; i++)
{
    array[i] = transform[array[i]];
}

answered Apr 5, 2014 at 14:21

p.s.w.g

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Comments

Filippo oretti · Accepted Answer · 2014-04-05 14:25:17Z

0

not tested but it should work

 var replaxe = {
     'c':'b',
     'e':'d'
    },
  array = ['c','e'],
  result = [];

  for(var item in array){
    result.push(replaxe[item]);
  }


  console.log(result);

edited Apr 5, 2014 at 14:25

answered Apr 5, 2014 at 14:20

Filippo oretti

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Comments

vijay · Accepted Answer · 2014-04-05 14:29:48Z

0

RUN THIS IN YOUR FIRE BUG CONSOLE

var array = ['c','a','t','a'];
var myarray = [];
for(i=0; i<=array.length; i++)
{
    if(array[i] == 'c' )
    {
        array[i] = 'b'
    }
    if(array[i] == 'a' )
    {
        array[i] = 'e'
    }
    if(array[i] == 't' )
    { 
        array[i] = 'c'
    }
    if(array[i] == 'a' )
    {
        array[i] = 'a'
    }
}

console.log(myarray);

edited Apr 5, 2014 at 14:29

answered Apr 5, 2014 at 14:24

vijay

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1 Comment

Bergi Over a year ago

Please use a reasonable indentation, put your text out of the code, and don't shout (caps).

Chirag Bhatia - chirag64 · Accepted Answer · 2014-04-05 14:32:16Z

0

I would recommend using a switch-case for every element in the array.

for (i in array) {
    switch (array[i]) {
    case "c":
        array[i] = "b";
        break;
    case "a":
        array[i] = "e";
        break;
    case "t":
        array[i] = "c";
        break;
    }
}

answered Apr 5, 2014 at 14:32

Chirag Bhatia - chirag64

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2 Comments

Bergi Over a year ago

replace? Seriously? Also don't use for in on arrays

Chirag Bhatia - chirag64 Over a year ago

@Bergi That was really stupid of me. Just a bit tired after a busy day.

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