CODEWITHSUNDEEP
javascriptarrays
Mindi Torrey
Mindi Torrey

Reputation: 325

Use map function to decode a string with an array of numbers

I am trying to write a decode function where the arguments are a string of letters (in this case the alphabet) and an array of numbers. I want to use the .map method on the array to return the coded message as a string. The numbers are positive integers.

The function, given the array passed in, should return the string "beans".

I cannot figure out the logic. Here is what I have:

function decoder(key, code) {
  var arr = key.split('');
  var result = "";
  arr.map(function(item) {
    for(var i = 0; i <= code.length; i++) {  
      if(item[i] === code[i]) {
        result += item;
      }
    }
    return result;
  });

}

console.log(decoder("abcdefghijklmnopqrstuvwxyz", [1, 4, 0, 13, 18 ]));

Upvotes: 0

Views: 733

Answers (3)

user5591717
user5591717

Reputation:

Others have already given a more solid solution, but you can use your initial idea of utilizing a for loop.

function decoder(key, code) {
    var arr = key.split('');

    var result = "";

    for (var i = 0; i < code.length; i++) {
        result += arr[code[i]];
    }

    return result;
}

console.log(decoder("abcdefghijklmnopqrstuvwxyz", [1, 4, 0, 13, 18 ]));

Upvotes: 1

madox2
madox2

Reputation: 51881

You can map code array to get character at each position and then join it:

function decoder(key, code) {
    return code.map(function(c) {
        return key.charAt(c);
    }).join('');
}

console.log(decoder("abcdefghijklmnopqrstuvwxyz", [1, 4, 0, 13, 18 ]));

Upvotes: 1

Meiko Rachimow
Meiko Rachimow

Reputation: 4724

A perfect match for Array.prototype.reduce():

function decoder(arr, indices){
  return indices.reduce(function(previousValue, currentValue){
    return previousValue + arr[currentValue];
  }, "");
}

alert(decoder("abcdefghijklmnopqrstuvwxyz", [1, 4, 0, 13, 18 ]));

Upvotes: 3

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