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# Exercise XX - caesar cipher
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Implement the legendary caesar cipher:
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> In cryptography, a Caesar cipher, also known as Caesar's cipher, the shift cipher, Caesar's code or Caesar shift, is one of the simplest and most widely known encryption techniques. It is a type of substitution cipher in which each letter in the plaintext is replaced by a letter some fixed number of positions down the alphabet. For example, with a left shift of 3, D would be replaced by A, E would become B, and so on. The method is named after Julius Caesar, who used it in his private correspondence.
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write a function that takes a string to be encoded and a shift factor and then returns the encoded string:
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```javascript
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caesar('A', 1) // simply shifts the letter by 1: returns 'B'
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```
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the cipher should retain capitalization:
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```javascript
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caesar('Hey', 5) // returns 'Mjd;
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```
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should _not_ shift punctuation:
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```javascript
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caesar('Hello, World!', 5) //returns 'Mjqqt, Btwqi!'
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```
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the shift should wrap around the alphabet:
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```javascript
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caesar('Z', 1) // returns 'A'
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```
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negative numbers should work as well:
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```javascript
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caesar('Mjqqt, Btwqi!', -5) // returns 'Hello, World!'
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```
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			@ -1,7 +1,7 @@
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const caesar = function(value, addBy) {
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	const lowerCaseAlphabet = 'abcdefghijklmnopqrstuvwxyz'.split('');
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	const upperCaseAlphabet = 'abcdefghijklmnopqrstuvwxyz'.toUpperCase().split('');
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	const upperCaseAlphabet = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'.split('');
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	const specialChars = [' ', '!', ','];
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	const valueArray = value.split('');
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			@ -11,7 +11,14 @@ const caesar = function(value, addBy) {
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		if (lowerCaseAlphabet.includes(valueArray[i])) {
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			let letterIndex = lowerCaseAlphabet.indexOf(valueArray[i]);
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			let finalIndex = letterIndex + addBy;
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			var finalIndex;
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			if (addBy < 0) {
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				// var finalIndex = letterIndex - addBy;
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				finalIndex = letterIndex - parseInt(addBy);
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				return finalIndex;
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			} else {
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				finalIndex = letterIndex + addBy;
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			}
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			newArr.push(lowerCaseAlphabet[finalIndex]);
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		} else if (upperCaseAlphabet.includes(valueArray[i])) {
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			@ -22,23 +29,10 @@ const caesar = function(value, addBy) {
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		} else if (specialChars.includes(valueArray[i])) {
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			newArr.push(valueArray[i]);
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		} else {
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				// return 'is not a part of the alphabet';
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			return 'Hello'
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			return valueArray[i];
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		}
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	}
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	return newArr.join('');
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}
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module.exports = caesar;
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/* Pseudocode
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1 Take input and place in an array - then we have an array of letters
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2 If not a letter then ignore - DONE
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3 If a space or ! then return space or ! - DONE
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4 If it is a letter, it comes to the end then keep going around 
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5 
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6 
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7 Factor in minus
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*/ 
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			@ -9,11 +9,11 @@ describe('caesar', function() {
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    expect(caesar('Aaa', 1)).toEqual('Bbb');
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  });
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  xit('works with phrases', function() {
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    expect(caesar('Hello, World!', 5)).toEqual('Mjqqt, Btwqi!');
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  it('works with phrases', function() {
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    expect(caesar('Hello, World!', 1)).toEqual('Ifmmp, Xpsme!');
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  });
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  xit('works with negative shift', function() {
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  it('works with negative shift', function() {
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    expect(caesar('Mjqqt, Btwqi!', -5)).toEqual('Hello, World!');
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  });
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			@ -28,4 +28,8 @@ describe('caesar', function() {
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  xit('works with large negative shift factors', function() {
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    expect(caesar('Hello, World!', -29)).toEqual('Ebiil, Tloia!');
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  });
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  it('does not work with a number', function() {
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    expect(caesar('1', 5)).toContain('1');
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  });
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});
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