freeCodeCamp/guide/english/certifications/javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/binary-agents/index.md

---
title: Binary Agents
---
# Binary Agents

---
## Problem Explanation

This problem is very straight forward - you start with a string that represents a sentence in binary code, and you need to translate that into words. There is not a direct way to do this so you will have to translate twice.

#### Relevant Links

*   <a href='http://forum.freecodecamp.com/t/javascript-string-prototype-charcodeat/15933' target='_blank' rel='nofollow'>String.prototype.charCodeAt</a>
*   <a href='https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/fromCharCode' target='_blank' rel='nofollow'>String.fromCharCode</a>


---
## Hints

### Hint 1

You should first convert from **binary** to **decimal** before translating those values into characters.

### Hint 2

Things are easier when focusing on smaller parts, divide the input to focus on one letter at a time.

### Hint 3

Make sure that each time you transcode a character from binary to decimal, you reset whatever variable you used to keep track of the ones. Also do not forget to turn everything back into one string.


---
## Solutions

<details><summary>Solution 1 (Click to Show/Hide)</summary>

```javascript
function binaryAgent(str) {
  var biString = str.split(" ");
  var uniString = [];

  /*using the radix (or base) parameter in parseInt, we can convert the binary
      number to a decimal number while simultaneously converting to a char*/

  for (var i = 0; i < biString.length; i++) {
    uniString.push(String.fromCharCode(parseInt(biString[i], 2)));
  }

  // we then simply join the string
  return uniString.join("");
}

// test here
binaryAgent(
  "01000001 01110010 01100101 01101110 00100111 01110100 00100000 01100010 01101111 01101110 01100110 01101001 01110010 01100101 01110011 00100000 01100110 01110101 01101110 00100001 00111111"
);
```

#### Code Explanation

*   Separate the string into an array of strings separated by whitespace.
*   Create some variables that you will use along the way - the names are self explanatory for the most part.
*   Iterate through each binary string in the new array.
*   Convert to decimal by using `parseInt(_binary_, 2)`. Use the second parameter to specify the base of the input numbers.
*   At the end, return the converted message.

#### Relevant Links

*   <a href='http://forum.freecodecamp.com/t/javascript-string-prototype-split/15944' target='_blank' rel='nofollow'>String.prototype.split</a>
*   <a href='https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/parseInt' target='_blank' rel='nofollow'>parseInt</a>
</details>

<details><summary>Solution 2 (Click to Show/Hide)</summary>

```javascript
function binaryAgent(str) {
  // Separate the binary code by space.
  str = str.split(" ");
  var power;
  var decValue = 0;
  var sentence = "";

  // Check each binary number from the array.
  for (var s = 0; s < str.length; s++) {
    // Check each bit from binary number
    for (var t = 0; t < str[s].length; t++) {
      // This only takes into consideration the active ones.
      if (str[s][t] == 1) {
        // This is quivalent to 2 ** position
        power = Math.pow(2, +str[s].length - t - 1);
        decValue += power;

        // Record the decimal value by adding the number to the previous one.
      }
    }

    // After the binary number is converted to decimal, convert it to string and store
    sentence += String.fromCharCode(decValue);

    // Reset decimal value for next binary number.
    decValue = 0;
  }

  return sentence;
}

// test here
binaryAgent(
  "01000001 01110010 01100101 01101110 00100111 01110100 00100000 01100010 01101111 01101110 01100110 01101001 01110010 01100101 01110011 00100000 01100110 01110101 01101110 00100001 00111111"
);
```

#### Code Explanation

*   For each of these binary strings, check for the ones and ignore the zeroes.
*   For those that are one or active then convert them to decimal, this takes into account the position and the right power it needs to be raised to.
*   Store the power into the **power** variable by adding it to any previous ones on the variable **decValue**. This variable will add and add the powers of the active ones until the end of the loop and then return the decimal number.
*   Convert the final decimal outside of the inner loop and then convert it to ASCII and saving it to **sentence** along with any other text string already converted and stored.
*   Reset the variable **decValue** to avoid getting wrong decimals before continuing to the outer loop.

#### Relevant Links

*   <a href='http://forum.freecodecamp.com/t/javascript-math-pow/14685' target='_blank' rel='nofollow'>Math.pow</a>
*   <a href='https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/length' target='_blank' rel='nofollow'>String.length</a>
</details>

<details><summary>Solution 3 (Click to Show/Hide)</summary>

```javascript
function binaryAgent(str) {
  return String.fromCharCode(
    ...str.split(" ").map(function(char) {
      return parseInt(char, 2);
    })
  );
}

// test here
binaryAgent(
  "01000001 01110010 01100101 01101110 00100111 01110100 00100000 01100010 01101111 01101110 01100110 01101001 01110010 01100101 01110011 00100000 01100110 01110101 01101110 00100001 00111111"
);
```

#### Code Explanation

*   First we use `split()` to be able to work on each character as an Array element
*   Then use `map()` to process each element from binary to decimal using `pareseInt()`
*   Last we can use `String.fromCharCode()` to convert each ASCII number into the corresponding character
*   However `fromCharCode()` expects a series of numbers rather than an Array! We can use ES6 Spread Operator to pass in an Array of numbers as individual numbers. See here for more info; <a href='https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Spread_operator' target='_blank' rel='nofollow'>Spread Operator</a>

#### Relevant Links

*   <a href='http://forum.freecodecamp.com/t/javascript-array-prototype-map/14294' target='_blank' rel='nofollow'>Array.prototype.map</a>

## Alternative Advanced Code Solution:
```js
  const binaryAgent = str => str.replace(/\d+./g, char => String.fromCharCode(`0b${char}`));
       
  binaryAgent("01000001 01110010 01100101 01101110 00100111 01110100 00100000 01100010 01101111 01101110 01100110 01101001 01110010 01100101 01110011 00100000 01100110 01110101 01101110 00100001 00111111");
```

#### Code Explanation

*   Find all groups of one or more digits followed by one other character
*   Replace with a string created from the specified sequence of UTF-16 code units
*   Use `0b` to lead the code unit to express that a binary integer literal is being converted. 

#### Relevant Links

*   <a href='https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/fromCharCode' target='_blank' rel='nofollow'>String.fromCharCode()</a>
*   <a href='https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/replace' target='_blank' rel='nofollow'>String.prototype.replace()</a>
*   <a href='https://codegolf.stackexchange.com/questions/35096/convert-a-string-of-binary-characters-to-the-ascii-equivalents' target='_blank' rel='nofollow'>Convert a string of binary characters to the ASCII equivalents</a>
*   <a href='https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Grammar_and_types#Numeric_literals' target='_blank' rel='nofollow'>Grammar and types/Numeric Literals</a>

</details>