Replace string with values from two arrays

Question

I have a string for example:

var string = 'This is a text that needs to change';

And then I have two arrays.

var array1 = new Array('a', 'e', 'i', 'o', 'u');
var array2 = new Array('1', '2', '3', '4', '5');

Now, what I what to do is check string with array1 and replace the string with corresponding value from array 2. So with a function to do this I need to get something like:

string = 'Th3s 3s 1 t2xt th1t n22ds to ch1ng2';

Any ideas on how to approach this problem? And may be an efficient approach? Since I plan to use this on huge chunks of data.

EDIT:

Based on the answers here I have compiled a code to allow the above operations while also allowing few special characters. Check it out.

var string = 'This is a text that needs to change';

var array1 = new Array('ee', 'a', 'e', 'i', 'o', ']');
var array2 = new Array('!', '1', '2', '3', '4', '5');

function escapeString(str){
    return str.replace(/[\-\[\]\/\{\}\(\)\*\+\?\.\\\^\$\|]/g, "\\$&");
}

var re = new RegExp('(' + escapeString(array1.join('ૐ')) + ')', 'g');
var nx = new RegExp(re.source.replace(/ૐ/g, "|"), 'g');
alert(nx);
var lookup = {};
for (var i = 0; i < array1.length; i++) {
    lookup[array1[i]] = array2[i];
}

string = string.replace(nx, function(c){
  return lookup[c]
});

alert(string);

Answer 1

for(var x = 0 ; x < array1.length; x++)
    string = string.replace(new RegExp(array1[x], "g"), array2[x])

FIDDLE

Answer 2

If the characters to replace are just regular letters, and nothing that has a special meaning in a regular expression, then you can make a regular expression that matches only those characters. That allows you to use a single replace with a function that translates those characters:

var string = 'This is a text that needs to change';

var array1 = new Array('a', 'e', 'i', 'o', 'u');
var array2 = new Array('1', '2', '3', '4', '5');

var str1 = array1.join('');
var re = new RegExp('[' + str1 + ']', 'g');

string = string.replace(re, function(c){
  return array2[str1.indexOf(c)]
});

Demo: http://jsfiddle.net/Guffa/2Uc92/

Answer 3

This sets up 1 RegExp and calls replace only once.

var string = 'This is a text that needs to change';
var array1 = new Array('a', 'e', 'i', 'o', 'u');
var array2 = new Array('1', '2', '3', '4', '5');

var regex = new RegExp( '['+array1.join('')+']', 'g' );

var lookup = {}; // Setup a hash lookup
for( var i=0 ; i<array1.length ; ++i )
    lookup[array1[i]] = array2[i];

string.replace(regex, function(c) { return lookup[c]; });
// "Th3s 3s 1 t2xt th1t n22ds t4 ch1ng2"

http://jsfiddle.net/2twr2/

Answer 4

Assuming your two arrays have the same size:

for(var i = 0; i < array1.length; i++){
    mystr = mystr.replace(array1[i], array2[i]);
}

Answer 5

Here's an example:

var string = 'This is a text that needs to change';

var vowels = ['a','e','i','o','u'];
var numbers = [1,2,3,4,5];

var result = string.replace(/./g, function(char) {
  var idx = vowels.indexOf(char);
  return idx > -1 ? numbers[idx] : char;
});
//^ Th3s 3s 1 t2xt th1t n22ds t4 ch1ng2

Answer 6

For the purpose of exploring other interesting methods of doing the same thing, here is an implementation using array map.

It's just another cool way of doing it, without using a loop, replace or regexp.

var string = 'This is a text that needs to change';
var array1 = ['a', 'e', 'i', 'o', 'u'];
var array2 = ['1', '2', '3', '4', '5'];

var a = string.split('');
a.map(function(c) {
    if (array1.indexOf(c) != -1) {
        a[ a.indexOf(c) ] = array2[ array1.indexOf(c) ];
    }
});

var newString = a.join('');
alert( newString );
//Outputs "Th3s 3s 1 t2xt th1t n22ds t4 ch1ng2"

Demo: JSFiddle

Interesting blog post about the array methods - map and reduce.

I'd love to hear thoughts about performance of array map vs the other methods.