Replacing Letters In A String Using Two Arrays?

var str = 'ajdisoiureenvmcnmvm' var arr1 = ['e','t','a','i','n','o','h','r','d','q','l','c','u','m','w','f','s','g','y','p','b','v','k','j','x','z'] var arr2 = ['m','i'

Solution 1:

If you're fine with map:

functionencode (string) {
  returnstring.split("").map(function (letter) {
    return arr1[arr2.indexOf(letter)];
  }).join("");
}

Solution 2:

This should be self explanatory and relatively efficient.

str = str.split("")
for(var i = 0; i < str.length; i++) {
    var c = str[i];
    var j = arr1.indexOf(c);
    str[i] = arr2[j];
}
str = str.join("");

I'd use a mapping for this kind of thing though.

Solution 3:

var str = "ajdisoiureenvmcnmvm"var arr1 = ["e","t","a","i","n","o","h","r","d","q","l","c","u","m","w","f","s","g","y","p","b","v","k","j","x","z"]
var arr2 = ["m","i","e","n","v","r","d","j","s","o","u","c","b","a","f","g","h","k","l","p","q","t","w","x","z","y"]

newStr = str.split("");
for (var i=0, len=newStr.length; i<len; i++)
{
    index = arr2.indexOf(newStr[i]);
    if(index>=0)
        newStr[i] = arr1[index];
}
str = newStr.join("");
console.log(str);

Solution 4:

Probably a more straight forward approach is to put the original string into an array first so you can manipulate it more easily character by character:

var arr1 = ["e","t","a","i","n","o","h","r","d","q","l","c","u","m","w","f","s","g","y","p","b","v","k","j","x","z"];
var arr2 = ["m","i","e","n","v","r","d","j","s","o","u","c","b","a","f","g","h","k","l","p","q","t","w","x","z","y"];
var str = "ajdisoiureenvmcnmvm";
vardata = str.split(""), index;
for (var i = 0; i < arr2.length; i++) {
    index = str.indexOf(arr2[i]);
    if (index >= 0) {
        data[index] = arr1[i];
    }
}
// build the string back again
str = data.join("");

Working demo: http://jsfiddle.net/jfriend00/fAQTe/

Solution 5:

It depends on your definition of "efficient." With that structure, it's quite hard to be efficient. But something like this is functional and short:

var rex = newRegExp("[" + arr1.join("") + "]", "g");
var result = str.replace(rex, function(letter) {
    var index = arr1.indexOf(letter);
    return index === -1 ? letter : arr2[index];
});

Live Example | Live Source

There, we create a regular expression using a character class to match each of the source characters, then do a replacement operation using a function to look up the replacement (if any) from the arrays.

Now, if you can change the structure, there are better ways, like using a map rather than arr1.indexOf. E.g.:

varmap = {
    "e": "m",
    "t": "i",
    "a": "e",
    // ...
};

Then (this uses ES5's Object.keys, which can be shimmed if needed):

var rex = newRegExp("[" + Object.keys(map).join("") + "]", "g");
var result = str.replace(rex, function(letter) {
    return map[letter] || letter;
});