loops.js

/* This program converts a Fahrenheit temperature to Celsius.

Input:
 Fahrenheit temperature

Output:
 Fahrenheit temperature
 Celsius temperature

Example:
 Enter Fahrenheit temperature: 100
 100° Fahrenheit is 37.77777777777778° Celsius

 ...

 Enter Fahrenheit temperature or press <Enter> to quit: 

References:
 * http://sphinxcontrib-napoleon.readthedocs.io/en/latest/example_google.html
 * https://javascript.info/comments
 * http://www.mathsisfun.com/temperature-conversion.html
 * https://nodejs.org/api/process.html#processexitcode
 * https://javascript.info/try-catch
 * https://javascript.info/types
*/

constTEMPERATURE_DIFFERENCE=32;
constTEMPERATURE_RATIO=5/9;
constABSOLUTE_ZERO=-459.67;

main();

/**
 * Runs main program logic.
 */
functionmain(){
try{
while(true){
letfahrenheit=getFahrenheit();
if(fahrenheit===""){
break;
}
letcelsius=calculateCelsius(fahrenheit);
displayResults(fahrenheit,celsius);
displayTable(fahrenheit);
}
}catch(error){
output("Unexpected error:");
output(`${error.name}: ${error.message}`);
}
}

/**
 * Gets Fahrenheit temperature.
 * 
 * @returns {number} Fahrenheit temperature or empty string
 */
functiongetFahrenheit(){
while(true){
letfahrenheit=input("Enter Fahrenheit temperature or press <Enter> to quit: ");
if(fahrenheit===""){
returnfahrenheit;
}

if(isNaN(fahrenheit)){
output("Fahrenheit temperature must be a number.");
output(`TypeError: '${fahrenheit}' is not a number.`);
continue;
}

fahrenheit=Number(fahrenheit);

if(fahrenheit<ABSOLUTE_ZERO){
output("Fahrenheit temperature cannot be below absolute zero.");
output(`RangeError: ${fahrenheit} is less than ${ABSOLUTE_ZERO}.`);
continue;
}

returnfahrenheit;
}
}

/**
 * Converts Fahrenheit temperature to Celsius.
 * 
 * @param {number} Fahrenheit temperature
 * @returns {number} Celsius temperature
 * @throws TypeError if fahrenheit is not numeric.
 * @throws RangeError if fahrenheit is below absolute zero.
 */
functioncalculateCelsius(fahrenheit){
if(typeoffahrenheit!="number"){
throw(newTypeError(`'${fahrenheit}' is not a number.`))
}

if(fahrenheit<ABSOLUTE_ZERO){
throw(newRangeError(`'${fahrenheit}' is below absolute zero.`))
}

letcelsius=(fahrenheit-TEMPERATURE_DIFFERENCE)*TEMPERATURE_RATIO;
returncelsius;
}

/**
 * Displays Fahrenheit and Celsius temperatures.
 * 
 * @param {number} Fahrenheit temperature
 * @param {number} Celsius temperature
 */
functiondisplayResults(fahrenheit,celsius){
console.assert(typeoffahrenheit=="number");
console.assert(typeofcelsius=="number");

output(`${fahrenheit}° Fahrenheit is ${celsius}° Celsius`);
}

/**
 * Displays nearest multiples of 10 Fahrenheit and Celsius temperatures.
 * 
 * @param {number} Fahrenheit temperature
 */
functiondisplayTable(fahrenheit){
console.assert(typeoffahrenheit=="number");

output("");
output("F\tC")
letstart=Math.floor(fahrenheit/10)*10
for(letfahrenheit=start;fahrenheit<start+11;fahrenheit++){
letcelsius=calculateCelsius(fahrenheit);
output(`${fahrenheit.toFixed(1)}\t${celsius.toFixed(1)}`)
}
output("");
}

/**
 * Generic input function to get input in HTML, Node, or Rhino environments.
 * 
 * @param {string} text prompt
 * @returns {string} input
 */
functioninput(text){
if(typeofwindow==='object'){
returnprompt(text)
}
elseif(typeofconsole==='object'){
constrls=require('readline-sync');
letvalue=rls.question(text);
returnvalue;
}
else{
output(text);
letisr=newjava.io.InputStreamReader(java.lang.System.in);
letbr=newjava.io.BufferedReader(isr);
letline=br.readLine();
returnline.trim();
}
}

/**
 * Generic output function to display output in HTML, Node, or Rhino environments.
 * 
 * @param {string} text prompt
 * @returns {string} input
 */
functionoutput(text){
if(typeofdocument==='object'){
document.write(text);
}
elseif(typeofconsole==='object'){
console.log(text);
}
else{
print(text);
}
}

Try It

See Also