as part of a javascript course I’ve written a simple Caesar cypher script. I want to phrase it as a function but don’t quite understand the syntax of functions.#
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var userinput = prompt("What's your message?"); //get user input
let alphabet = "abcdefghijklmnopqrstuvwxyz"; //define alphabet
let alphabetupper = alphabet.toUpperCase(); //define alphabet uppercase (else it gets messy to do the lookup!)
let shift=15; //define letter shift
//___________________________________________
let result = "";
for (let i = 0; i < userinput.length; i++) {
let letter = userinput[i]; //declare letter as userinput char at index
if (letter.toLowerCase()==letter.toUpperCase()){ //if its not a letter...
result +=letter; //print it to result
}
else if ((letter===letter.toUpperCase())) { //else if it is an uppercase letter...
let j=alphabetupper.indexOf(letter); //get index of letter in alphabet "j"
if ((j+shift)<25){ //check shift pos is less than end of alphabet
result+= ((alphabetupper[j+shift])); //print uppercase letter 15 places forward of result
}
else if ((j+shift)>25){ //if the new index is past z...
result+=((alphabetupper[j+(shift-26)])); //loop past z
}
}
else if (/*(letter.toLowerCase()!==letter.toUpperCase())&&*/(letter==letter.toLowerCase())) { //if it is a lowercase letter...
let j=alphabet.indexOf(letter); //get index of letter in alphabet "j"
if ((j+shift)<25){ //check shift pos is less than end of alphabet
result+= (alphabet[j+shift]); //print letter 15 places forward to result
}
else if ((j+shift)>25){ //if the new index is past z...
result+=(alphabet[j+(shift-26)]); //loop past z
}
}
};
alert(("Your encoded message is ") + (result)); //Output result
>Solution :
All you have to do now is run the code i called the function in the last line
function ceasar (userinput){
var userinput = prompt("What's your message?"); //get user input
let alphabet = "abcdefghijklmnopqrstuvwxyz"; //define alphabet
let alphabetupper = alphabet.toUpperCase(); //define alphabet uppercase (else it gets messy to do the lookup!)
let shift=15; //define letter shift
//___________________________________________
let result = "";
for (let i = 0; i < userinput.length; i++) {
let letter = userinput[i]; //declare letter as userinput char at index
if (letter.toLowerCase()==letter.toUpperCase()){ //if its not a letter...
result +=letter; //print it to result
}
else if ((letter===letter.toUpperCase())) { //else if it is an uppercase letter...
let j=alphabetupper.indexOf(letter); //get index of letter in alphabet "j"
if ((j+shift)<25){ //check shift pos is less than end of alphabet
result+= ((alphabetupper[j+shift])); //print uppercase letter 15 places forward of result
}
else if ((j+shift)>25){ //if the new index is past z...
result+=((alphabetupper[j+(shift-26)])); //loop past z
}
}
else if (/*(letter.toLowerCase()!==letter.toUpperCase())&&*/(letter==letter.toLowerCase())) { //if it is a lowercase letter...
let j=alphabet.indexOf(letter); //get index of letter in alphabet "j"
if ((j+shift)<25){ //check shift pos is less than end of alphabet
result+= (alphabet[j+shift]); //print letter 15 places forward to result
}
else if ((j+shift)>25){ //if the new index is past z...
result+=(alphabet[j+(shift-26)]); //loop past z
}
}
};
alert(("Your encoded message is ") + (result)); //Output result
}
ceasar();