Question about functions and returns in javascript

Question

I am trying to create a function that converts celcius to fahrenheit and vice versa using a return statement inside. I'm confused why the code below won't return or log anything on the console but the bottom bit of code will.

function convertTemp2(degrees,unit) {
  if (unit === 'F' || unit === 'C') {
    conversion(degrees,unit);
    console.log(`${degrees} ${unit}`)
  } else {
    console.log('please use C for celcius, and F for fahrenheit');
  }
}

function conversion(degrees,unit) {
  if (unit === 'F') {
    degrees = (degrees+32) *5/9;
    unit = 'C';
    return degrees, unit;
  } else if (unit === 'C') {
    degrees = (degrees*9/5) + 32;
    unit = 'F';
    return degrees, unit;
  }
}

convertTemp2(1023,'F');
convertTemp2(12,'C');
convertTemp2(123,'H');

This seems to work:

function convertTemp2(degrees,unit) {
  if (unit === 'F' || unit === 'C') {
    conversion(degrees,unit);
  } else {
    console.log('please use C for celcius, and F for fahrenheit');
  }
}

function conversion(degrees,unit) {
  if (unit === 'F') {
    degrees = (degrees+32) *5/9;
    console.log(`${degrees}C`)
  } else if (unit === 'C') {
    degrees = (degrees*9/5) + 32;
    console.log(`${degrees}F`)
  }
}

convertTemp2(1023,'F');
convertTemp2(12,'C');
convertTemp2(123,'H');

Answer 1

it should look like

function convertTemp2(degrees,unit) {
  if (unit === 'F' || unit === 'C') {
    const {a, b} = conversion(degrees,unit);
    console.log(`${a} ${b}`)
  } else {
    console.log('please use C for celcius, and F for fahrenheit');
  }
}

function conversion(degrees,unit) {
  let a, b
  if (unit === 'F') {
    a = (degrees+32) *5/9;
    b = 'C';
    return {a,b};
  } else if (unit === 'C') {
    a = (degrees*9/5) + 32;
    b = 'F';
    return {a, b};
  }
}

convertTemp2(1023,'F');
// convertTemp2(12,'C');
// convertTemp2(123,'H');